Show lists in the inspector and variables in their own tab (#252)

The List tab could show one list at a time and was the only place to
see its items. A list now shows its items right where it lives, and a
new Variables tab shows all variables of an asset or placed object.

- InlineList draws the items of a list under its row in the inspector,
  in struct fields and in the Variables tab. A list inside a list or a
  struct field is drawn the same way, one step indented.
- The index column is the indent. Items sit under their list without an
  own margin, and the index column is 16 px wide instead of 28 px.
- Above 20 items (INLINE_LIMIT) the rest collapses into "... N more -
  open in tab". During a run the rows show the values from the game.
- ListHead puts "N items" and "+ Item" in one row. "N items" opens the
  list in a tab. A separate Open button squeezed the counter to zero
  width in the narrow inspector column.
- VariablesEditor shows every variable of a behavior asset, a variables
  asset or a placed behavior. On an asset it edits the declarations. On
  a placed object an edit only overrides that object, with the usual
  reset and push buttons.
- Opening a list inside a tab adds a new tab and keeps the open one.
  valuesKey gives each list its own document, so a list that is already
  open is shown instead of opened twice.
- Titles read "Pickup · Variables" or "Listy · nums · [3]". The tab
  closes when its asset or object is deleted.
- Lists on node inputs stay inline only, a node owns no variables.
- The List tab, ListEditor and the __gm.list hook are gone.

Tests:
- ./check.sh: 181 files, 2645 tests, CHECK EXIT 0
- GM_STEPS=1,21,22,32: ALL PASSED, 123 checks
- e2e 21 is rewritten for inline lists and the new tab, 22 and 32 are
  adapted. Sum in README: 1486 (+6 in 21, -1 in 22), counted by hand.
- Counter-probes fail as expected: sub-lists not told apart (1 unit
  test), sub-list replacing the open tab, all items drawn inline (60
  rows instead of 20), no live values (0 rows at 24 items in a run).

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

tools/e2e/lib/scaffold.mjs

@@ -170,12 +170,12 @@ const DOCUMENT_KINDS = [
   'curve',
   'tile',
   'container',
-  'list',
+  'variables',
   'management',
 ];
 
 /**
- * Clicks the tab of an open document (`asset:<id>` or `list`), through the `»` menu when the row
+ * Clicks the tab of an open document (`asset:<id>` or `values:<key>`), through the `»` menu when the row
  * hides it. The press lands left of the ×, on the name.
  */
 export async function clickDocumentTab(t, doc) {
@@ -188,7 +188,7 @@ export async function clickDocumentTab(t, doc) {
   if (!row.hidden.includes(doc)) throw new Error(`no tab for ${doc}`);
   const label = await t.json(`(() => {
     const id = ${JSON.stringify(doc)};
-    if (id === 'list') return null;
+    if (id.startsWith('values:')) return __gm.tabRow().labels?.[id] ?? null;
     const asset = __gm.state.project.assets.find((a) => 'asset:' + a.id === id);
     return asset ? asset.name : null;
   })()`);