Three stores, three importers and three pickers that differ only in their type are one of each (#85)

Refactoring round one: HttpFontStore/HttpSoundStore/HttpTextureStore collapse into a generic
HttpFileStore over a FileStore contract; fontImport/soundImport/textureImport share assetImport
with an ImportKind per sort; ImagePicker/FontPicker/SoundPicker sit on FilePicker and describe
only their row. The group/comment drag logic leaves GraphCanvas for annotationDrag.ts (with its
own unit test), declaredRows.ts replaces the duplicated row build in particles.ts and shaders.ts,
and dead code in font/sound/compile/emission/transform/actions is gone. README: asset list,
check count 958, the two-job CI, the Scenes wiki page.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/core/store/TextureStore.ts

@@ -1,38 +1,18 @@
-export interface UploadedTexture {
-  /** Content-addressed name in `data/textures/`: `{sha256}.{png|jpg|webp|gif}` (see `isTextureFile`). */
-  file: string;
-  /**
-   * The name the file was uploaded under, '' when the server knows none. A picture may be
-   * re-encoded on the way, so this can be a `.png` name on a file stored as `.webp`.
-   */
-  name: string;
+import type { FileStore, StoredFile, UploadedFile } from './FileStore';
+
+/**
+ * Stored in `data/textures/` as `{sha256}.{png|jpg|webp|gif}`. A picture may be re-encoded on the
+ * way, so `name` can be a `.png` name on a file stored as `.webp`.
+ */
+export interface UploadedTexture extends UploadedFile {
   width: number;
   height: number;
-  bytes: number;
 }
 
-/** A file the server holds, whether any project references it or not. */
-export interface StoredTexture {
-  file: string;
-  name: string;
+export interface StoredTexture extends StoredFile {
   /** 0 × 0 when the server could not read the header; such a file cannot become an asset. */
   width: number;
   height: number;
-  bytes: number;
-  updatedAt: string;
 }
 
-/**
- * An upload is raw bytes rather than a multipart form: name, size and format are derived from the
- * image itself on the server, so there is nothing else to send.
- */
-export interface TextureStore {
-  /**
-   * `type` only fills the Content-Type header – the server trusts the bytes, not the label – and
-   * uploading the same picture twice yields the same file, the hash of its content. `name` is the
-   * caption kept beside it; uploading the same bytes under a new name renames what pickers show.
-   */
-  upload(bytes: Blob | ArrayBuffer, type: string, name?: string): Promise<UploadedTexture>;
-  list(): Promise<StoredTexture[]>;
-  delete(file: string): Promise<void>;
-}
+export type TextureStore = FileStore<UploadedTexture, StoredTexture>;