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/particles/compile.ts

@@ -38,18 +38,6 @@ export interface ParticlesBuild {
   reason: string;
 }
 
-/**
- * What the motion depends on and nothing else: node ids, types, params and declared ports, and
- * which port feeds which. Positions and folding are the editor's, so a moved node does not compile
- * again – the same rule the shader fingerprint follows (#65).
- */
-export function particlesFingerprint(graph: Graph): string {
-  return JSON.stringify({
-    nodes: graph.nodes.map((n) => [n.id, n.type, n.params, n.ports ?? null]),
-    edges: graph.edges.map((e) => [e.from.node, e.from.port, e.to.node, e.to.port]),
-  });
-}
-
 /**
  * A particle graph to one function per output: every node reachable from the Output becomes one
  * local per output, in dependency order, so a node feeding two others is evaluated once per