feat(api): upload queue with quota, tus intake, processing and import (M5.5)

- Migration 00008: upload_batches, upload_files, upload_quota.
- Quota reserved under a row lock when a batch is created; every status
  change goes through one transition that frees space in the same
  transaction. SHA-256 duplicates are rejected before any upload.
- tus 1.0.0 core (HEAD/PATCH) for the author only; offset is the real
  staging file size, data beyond the declared size is refused (ADR-015).
- Processing worker: ffprobe checks, SHA-256 verification, exact and
  Chromaprint duplicates against library and queue, metadata from tags
  or the dropped folder path, possible_duplicate on metadata match, and
  the target path from write_template reusing existing folder spelling.
- Import worker: edited tags written with ffmpeg stream copy, file
  written by storage-agent, point scan of the new file, imported status;
  idempotent and resumed after restart. Stale uploads expire after 24 h,
  orphan staging files are removed at startup.
- API: quota, precheck, batches, my uploads, withdraw, admin list,
  metadata edit, bulk review, retry and queue settings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/i18n/locales/en/errors.json

@@ -76,5 +76,22 @@
   },
   "app": {
     "update_unavailable": "Update is unavailable"
+  },
+  "uploads": {
+    "queue_full": "The upload queue is full",
+    "user_quota_full": "Your upload queue limit is exceeded",
+    "too_large": "The file is larger than allowed",
+    "duplicate": "This track is already in the library or in the queue",
+    "invalid_audio": "The file does not look like audio (one audio stream, 5 s to 3 h)",
+    "unsupported_format": "Unsupported format: FLAC, MP3, M4A, OGG, Opus, WAV, AIFF and WavPack are accepted",
+    "not_found": "Upload not found",
+    "wrong_status": "The file is already in another status; refresh the page",
+    "no_target": "No storage accepts uploads (or several do and none is the default)",
+    "no_template": "The storage has no path template",
+    "missing_field": "Not enough metadata to build the storage path",
+    "offset_mismatch": "The upload got out of sync; try again",
+    "size_mismatch": "The file size does not match the declared one",
+    "hash_mismatch": "The file was corrupted in transit (SHA-256 mismatch)",
+    "import_failed": "Could not write the file to the storage"
   }
 }