feat(frontend): avatar upload QOL — feedback, re-crop, drop, progress, history

Task 12 batch around the existing crop/preview flow:
- Success Notice (auto-dismiss ~2.5s) after an avatar upload.
- "Reposition" re-crops the current avatar without re-picking a file.
- Drag & drop an image straight onto the profile avatar circle.
- Real upload progress via a new XHR-backed api.upload (fetch has none);
  refreshOnce now also stores the renewed token (reload-restore fix).
- Local avatar history (last 5, IndexedDB, this-device-only) strip that
  re-uploads a stored crop. Stored as ArrayBuffer (Blob is not cloneable
  under structuredClone); label makes the per-device scope explicit.
- Added a "success" tone to Notice.

Infra (same session): registered @shared/@features/@pages/@app/@test path
aliases in vite.config + tsconfigs and rewrote deep ../../../ imports;
moved avatar components into components/avatar/ to keep folders at <=4 files.

Tests: avatarHistory cap/order, recrop visibility, drop-opens-cropper,
client upload/progress/401-retry. bun test 103 pass, lint 0 errors, build ok.

frontend/bun.lock

@@ -28,6 +28,7 @@
         "@types/react": "^19.2.18",
         "@types/react-dom": "^19.2.7",
         "@vitejs/plugin-react": "^6.1.1",
+        "fake-indexeddb": "^6.2.5",
         "jsdom": "^30.1.1",
         "oxlint": "^1.81.0",
         "typescript": "^7.0.2",
@@ -335,6 +336,8 @@
 
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+    "fake-indexeddb": ["fake-indexeddb@6.2.5", "", {}, "sha512-CGnyrvbhPlWYMngksqrSSUT1BAVP49dZocrHuK0SvtR0D5TMs5wP0o3j7jexDJW01KSadjBp1M/71o/KR3nD1w=="],
+
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     "framer-motion": ["framer-motion@13.4.3", "", { "dependencies": { "motion-dom": "^13.4.2", "motion-utils": "^13.3.0", "tslib": "^2.4.0" }, "peerDependencies": { "react": "^18.0.0 || ^19.0.0", "react-dom": "^18.0.0 || ^19.0.0" }, "optionalPeers": ["react", "react-dom"] }, "sha512-mPQe1GtRHWS30zRGaQAfmlIg0baA0jRhkpbFPT1d+s9bZPjMW6pJSjWM6ArmUEjzMgEm089ZL1wd8aPv1/5DJQ=="],