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/properties/transform.ts

@@ -99,10 +99,6 @@ export function worldPosition(project: Project, tree: ObjectTree, object: SceneO
   return positionOf(worldTransform(project, tree, object));
 }
 
-export function editorPosition(project: Project, tree: ObjectTree, object: SceneObject): Position {
-  return positionOf(editorTransform(project, tree, object));
-}
-
 /** The world transform of a parent ('' = top level, the identity). */
 export function parentTransform(project: Project, tree: ObjectTree, parentId: string): ChainTransform {
   const parent = parentId ? findObject(tree, parentId) : undefined;