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/commands/graphCommands.ts

@@ -15,7 +15,7 @@ import type { Project } from '../model/Project';
 import { coerceValue, defaultsOf } from '../properties/PropertySchema';
 import { type Removed, removeById, removeFirst, removeWhere, restoreAt } from '../util/list';
 import { type Command, CommandError } from './Command';
-import { requireGraph, requireNode, requireNodeDef } from './require';
+import { requireEdge, requireGraph, requireNode, requireNodeDef } from './require';
 import { SetBagValueCommand } from './SetBagValueCommand';
 
 export class AddNodeCommand implements Command {
@@ -221,19 +221,13 @@ export class FoldEdgeCommand implements Command {
   }
 
   execute(project: Project): void {
-    const edge = this.edge(project);
+    const edge = requireEdge(project, this.assetId, this.edgeId);
     this.previous = edge.folded === true;
     this.apply(edge, this.folded);
   }
 
   undo(project: Project): void {
-    this.apply(this.edge(project), this.previous);
-  }
-
-  private edge(project: Project): GraphEdge {
-    const edge = requireGraph(project, this.assetId).edges.find((e) => e.id === this.edgeId);
-    if (!edge) throw new CommandError(`Edge ${this.edgeId} not found`);
-    return edge;
+    this.apply(requireEdge(project, this.assetId, this.edgeId), this.previous);
   }
 
   private apply(edge: GraphEdge, folded: boolean): void {
@@ -254,19 +248,13 @@ export class NameTransitionCommand implements Command {
   ) {}
 
   execute(project: Project): void {
-    const edge = this.edge(project);
+    const edge = requireEdge(project, this.assetId, this.edgeId);
     this.previous = edge.label ?? '';
     this.apply(edge, this.name.trim());
   }
 
   undo(project: Project): void {
-    this.apply(this.edge(project), this.previous);
-  }
-
-  private edge(project: Project): GraphEdge {
-    const edge = requireGraph(project, this.assetId).edges.find((e) => e.id === this.edgeId);
-    if (!edge) throw new CommandError(`Edge ${this.edgeId} not found`);
-    return edge;
+    this.apply(requireEdge(project, this.assetId, this.edgeId), this.previous);
   }
 
   private apply(edge: GraphEdge, name: string): void {