Refactoring round 8: hide data files, safe saves, Esc as Cancel (#85)

Recurring cleanup round over the code since round 7 (bc688f3). The
issue now also asks to fix bugs and small inconsistencies found on the
way, so unlike the rounds before, this one changes behaviour in a few
places. Duplicated code in api went from 23 clones with 228 lines to
none (jscpd, at least 50 tokens). In src it stays at 22 clones with
271 lines, the same before and after.

Bugs:
- nginx served project and snapshot files as they were, so anyone who
  knew a project id could read it without signing in. Every file the
  API writes now goes through AtomicFile (temp file, mode, rename).
  Projects, snapshots, releases, accounts and sessions are 0640, and
  nginx answers 403 for them.
- Any signed-in account could delete a shared image, font or sound,
  which projects of other accounts may wear. Deleting one is now for
  administrators only. The editor never deleted a file, so the
  client's delete is gone.
- Two saves of one project could run at once. The lock file was
  removed after each save, so a waiting save and the next one locked
  different files. The lock file now stays, and deleting a project
  takes the lock as well.
- Bytes that are no picture got a 500 instead of a 422, because the
  error handler also threw for warnings silenced with @.
- A session file was rewritten in place. A request reading it at that
  moment found it empty and was signed out. It is replaced atomically.
- Delete did nothing for a shape picked in the vector art list. Delete
  now goes through removeSelection, one case per kind of selection,
  and a kind without a case fails the type check.

Inconsistencies:
- Escape on a question does what its Cancel does. Cancel on "Delete
  project?" and "Restore snapshot?" leads back to the picker or the
  list like the other questions did, and so does deleting a project.
- Editor texts use American spelling throughout, like the port names:
  48 British spellings in 45 lines (colour, centre, initialised).
- objectName and groupName replace eleven copies of "own name, else
  the asset's" and three of "Group". One copy fell back to the object
  id instead of "?".

Duplicates, dead code, comments:
- routeFiles serves images, fonts and sounds instead of three copies.
  HashedFileStore holds what the three stores shared: keeping a file
  under its hash with its name, listing and deleting. The stores keep
  only which bytes they take and what a record says.
- AtomicFile replaces nine copies of temp file plus rename.
- removeShapes is the one way the canvas, the inspector button and
  Delete take shapes out.
- GraphInterpreter.fire was called by tests only. The 54 calls use a
  helper in tests/helpers.ts now.
- FileStore.delete, HttpFileStore.delete and the PluginApi type were
  unused. A doc comment in actions.ts sat above the wrong function.

Checked and left as is:
- solidCells is used by tests only. It is the per-cell view before the
  merge into rectangles, the one place the largest-scale rule shows.
- An undo checker ran all 124 commands of the unit tests and compared
  the project before and after undo. The only differences are empty
  ports, groups and notes lists where there were none, which the file
  format drops anyway.

Docs:
- README: the check sum.
- Wiki, own commit: API (admin-only deletes, 422, file modes, lock
  file), Home (the "Not yet" list named three things that exist),
  Concepts, Keyboard, Vector art, Architecture and Development, and
  the 38 characters Gitea flagged as ambiguous on eight pages.
- .gitignore: the lock files, and pasted-*.png in any folder, which
  keeps the screenshot archive out.

Tests:
- ./check.sh: 195 files, 2817 tests, exit 0 (+2 for the name helpers).
- PHP: accounts 52 in the web container and 53 in the CI image with
  the race test (+2), snapshots 15 (+1), releases 20.
- Full e2e run: ALL PASSED, 1586 checks (+6 in 12, 47, 49 and 50).
- Smokes jumprun, tetris, actor: 24, 19 and 21 checks. The example
  project files were restored byte for byte afterwards.
- The file stores of HEAD and of this commit give byte-identical
  output for the live folders and for store, list and delete in a
  throwaway folder.
- Counter-checks, all fail as expected: a 500 for bad bytes fails 12,
  no admin check fails 49, removing the lock file again loses saves
  in 3 of 3 runs (151 to 170 of 321), Delete ignoring shapes fails 47,
  Escape that only closes fails 50, and dropping the shape case fails
  the type check (TS2366).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/lib/TextureStore.php

@@ -2,19 +2,13 @@
 declare(strict_types=1);
 
 /**
- * Content-addressed image store: `data/textures/{sha256}.{ext}`.
+ * Content-addressed image store: `data/textures/{sha256}.{ext}` (see HashedFileStore).
  *
- * The name of a file is the hash of its bytes, which buys four things at once:
- * uploading the same image twice costs one file, a stored file can be cached forever
- * (its URL cannot ever mean different bytes), projects reference a short string instead
- * of embedding megabytes of base64, and deleting a texture asset is undoable for free
- * because nothing here is removed when it stops being referenced.
- *
- * The flip side is that files outlive the projects that used them: nothing collects the
- * unreferenced ones. They stay pickable instead – `GET ?r=textures` is what the editor's
- * image picker offers, so a picture one project dropped is still there for the next.
+ * The flip side of hashed names is that files outlive the projects that used them: nothing
+ * collects the unreferenced ones. They stay pickable instead – `GET ?r=textures` is what the
+ * editor's image picker offers, so a picture one project dropped is still there for the next.
  */
-final class TextureStore
+final class TextureStore extends HashedFileStore
 {
     /** Accepted formats. SVG is deliberately absent: it can carry script. */
     private const EXTENSIONS = [
@@ -38,14 +32,6 @@ final class TextureStore
      */
     private const MAX_DIMENSION = 8192;
 
-    public function __construct(private readonly string $dir)
-    {
-        if (!is_dir($this->dir) && !mkdir($this->dir, 0775, true) && !is_dir($this->dir)) {
-            throw new RuntimeException("Cannot create texture directory {$this->dir}");
-        }
-    }
-
-    /** A stored file name, as it appears in a project document. */
     public static function isValidName(string $name): bool
     {
         return (bool) preg_match('/^[a-f0-9]{64}\.(png|jpg|webp|gif)$/', $name);
@@ -87,80 +73,20 @@ final class TextureStore
             throw new InvalidImageException('Image must be between 1 and ' . self::MAX_DIMENSION . ' pixels per side');
         }
 
-        $file = hash('sha256', $bytes) . '.' . $extension;
-        $path = $this->dir . '/' . $file;
-        if (!is_file($path)) {
-            $this->writeFile($path, $bytes);
-        }
-        OriginalName::write($this->dir, $file, $originalName);
-
-        return [
-            'file' => $file,
-            'name' => OriginalName::read($this->dir, $file),
-            'width' => $width,
-            'height' => $height,
-            'bytes' => strlen($bytes),
-        ];
+        return $this->keep($bytes, $extension, $originalName, ['width' => $width, 'height' => $height]);
     }
 
     /**
-     * Every stored file, newest first – what the image picker offers.
+     * The pixel size, read from each header rather than left to the client: a texture asset records
+     * the size, so a picker that only knew the file name could not create one without decoding the
+     * picture first. An unreadable file reports 0 × 0 and the picker skips it.
      *
-     * The pixel size is read from each header rather than left to the client: a texture asset
-     * records the size, so a picker that only knew the file name could not create one without
-     * decoding the picture first. An unreadable file reports 0 × 0 and the picker skips it.
-     *
-     * @return list<array{file:string,name:string,width:int,height:int,bytes:int,updatedAt:string}>
+     * @return array{width:int,height:int}
      */
-    public function list(): array
+    protected function details(string $path): array
     {
-        $items = [];
-        foreach (glob($this->dir . '/*.*') ?: [] as $path) {
-            $file = basename($path);
-            // Sidecars live in the same directory and are skipped here: `{hash}.png.json` is not
-            // a valid stored name.
-            if (!self::isValidName($file)) {
-                continue;
-            }
-            $size = @getimagesize($path);
-            $items[] = [
-                'file' => $file,
-                'name' => OriginalName::read($this->dir, $file),
-                'width' => (int) ($size[0] ?? 0),
-                'height' => (int) ($size[1] ?? 0),
-                'bytes' => (int) filesize($path),
-                'updatedAt' => gmdate('c', (int) filemtime($path)),
-            ];
-        }
-        usort($items, static fn(array $a, array $b): int => strcmp($b['updatedAt'], $a['updatedAt']));
-        return $items;
-    }
-
-    public function delete(string $file): bool
-    {
-        if (!self::isValidName($file)) {
-            return false;
-        }
-        $path = $this->dir . '/' . $file;
-        if (!is_file($path) || !unlink($path)) {
-            return false;
-        }
-        OriginalName::delete($this->dir, $file);
-        return true;
-    }
-
-    /**
-     * Writes via a temp file in the same directory, so a reader never sees a half-written
-     * image: the name only ever appears once the bytes behind it are complete.
-     */
-    private function writeFile(string $path, string $bytes): void
-    {
-        $tmp = $path . '.' . bin2hex(random_bytes(4)) . '.tmp';
-        if (file_put_contents($tmp, $bytes, LOCK_EX) === false || !rename($tmp, $path)) {
-            @unlink($tmp);
-            throw new RuntimeException('Cannot write texture file');
-        }
-        @chmod($path, 0664);
+        $size = @getimagesize($path);
+        return ['width' => (int) ($size[0] ?? 0), 'height' => (int) ($size[1] ?? 0)];
     }
 }