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>

tests/core/particles.test.ts

@@ -8,13 +8,15 @@ import { CreateAssetCommand, SetAssetPropertyCommand } from '../../src/core/comm
 import { AddNodeCommand, ConnectCommand, MoveNodeCommand } from '../../src/core/commands/graphCommands';
 import { isPlaceableType } from '../../src/core/model/AssetTypes';
 import { findAssetOf } from '../../src/core/model/Project';
+import { graphFingerprint } from '../../src/core/graph/Graph';
+import { compileParticles, emptyParticleOut, type ParticleOut } from '../../src/core/particles/compile';
 import {
-  compileParticles,
-  emptyParticleOut,
-  type ParticleOut,
-  particlesFingerprint,
-} from '../../src/core/particles/compile';
-import { birthTime, fieldTime, liveCount, liveRange, prewarmOffset } from '../../src/core/particles/emission';
+  birthTime,
+  fieldTime,
+  type LiveRange,
+  liveRange,
+  prewarmOffset,
+} from '../../src/core/particles/emission';
 import {
   hashId,
   mixColor,
@@ -222,11 +224,11 @@ describe('a particle asset', () => {
     const output = p.add(PARTICLE_OUTPUT);
     const n = p.add('ParticleNumber', { value: 2 });
     p.link(n, 'value', output, 'x');
-    const before = particlesFingerprint(p.asset().graph);
+    const before = graphFingerprint(p.asset().graph);
     f.stack.execute(new MoveNodeCommand(p.id, n, 120, 80));
-    expect(particlesFingerprint(p.asset().graph)).toBe(before);
+    expect(graphFingerprint(p.asset().graph)).toBe(before);
     f.stack.execute(new AddNodeCommand(p.id, 'ParticleNumber', 0, 0, { value: 5 }));
-    expect(particlesFingerprint(p.asset().graph)).not.toBe(before);
+    expect(graphFingerprint(p.asset().graph)).not.toBe(before);
   });
 
   it('survives a round trip through the project file, graph and rows intact', () => {
@@ -270,6 +272,8 @@ describe('a particle asset', () => {
   });
 });
 
+const liveCount = (range: LiveRange): number => Math.max(0, range.to - range.from + 1);
+
 describe('when particles are alive', () => {
   const settings = {
     mode: 'continuous' as const,