fix(web): stream large album uploads to disk (busboy) instead of buffering

Manual import used request.formData(), which buffers the whole body and caps out
around ~15MB — a real FLAC album is hundreds of MB (Hollywood's Bleeding is
584MB), so it failed with "expected multipart form data". Now the multipart body
is STREAMED with busboy: each file pipes straight to a hidden .import-<uuid>
staging dir on the library filesystem, then the dir is atomically renamed into
place. No full-body buffering, no size cap. Cleaned up on any failure; guards
(400 missing fields/audio, 409 exists) unchanged. web 161 tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/package.json

@@ -12,17 +12,19 @@
     "db:dev": "prisma migrate dev"
   },
   "dependencies": {
+    "@prisma/client": "6.1.0",
+    "@types/busboy": "^1.5.4",
+    "busboy": "^1.6.0",
     "next": "15.5.20",
     "react": "19.0.0",
-    "react-dom": "19.0.0",
-    "@prisma/client": "6.1.0"
+    "react-dom": "19.0.0"
   },
   "devDependencies": {
-    "typescript": "5.7.2",
     "@types/node": "22.10.2",
     "@types/react": "19.0.1",
     "@types/react-dom": "19.0.1",
     "prisma": "6.1.0",
+    "typescript": "5.7.2",
     "vitest": "2.1.8"
   }
 }