feat: finish the upload, playback, and test gaps from the docs

Quality upgrades, batch covers, staging preview, and resume after reload are in the queue. Loudness and crossfade work on web and Android, and the documented checks now have suites.

Co-authored-by: Cursor <cursoragent@cursor.com>

packages/i18n/locales/en/admin.json

@@ -203,6 +203,11 @@
     "skipped_few": "{{count}} files skipped — not audio",
     "skipped_many": "{{count}} files skipped — not audio",
     "skipped_other": "{{count}} files skipped — not audio",
+    "resume_hint_one": "{{count}} file was not finished. Pick it again to resume.",
+    "resume_hint_few": "{{count}} files were not finished. Pick them again to resume.",
+    "resume_hint_many": "{{count}} files were not finished. Pick them again to resume.",
+    "resume_hint_other": "{{count}} files were not finished. Pick them again to resume.",
+    "resume_pick": "Pick files and resume",
     "comment": "Comment for the administrator",
     "comment_hint": "For example: “2011 remaster”, “replacing broken files”",
     "not_enough_space": "The queue is short of space: {{need}} needed, {{free}} free — some files will be refused.",
@@ -275,6 +280,14 @@
     "disc": "disc {{n}}",
     "edited": "edited",
     "flag_possible": "possible duplicate",
+    "flag_quality": "better quality",
+    "listen": "Listen to {{name}}",
+    "edit_batch": "Whole batch",
+    "batch_edit_title": "Edit batch",
+    "batch_edit_hint": "Empty fields stay as they are. The cover is written into the files on import.",
+    "batch_cover": "Batch cover",
+    "batch_cover_clear": "Remove cover",
+    "set_upgrade": "Accept the same track in better quality",
     "flag_existing_album": "existing album",
     "flag_new_album": "new album",
     "dup_level_sha256": "exact copy of a file",
@@ -332,7 +345,8 @@
       "uploading": "Uploading",
       "done": "Uploaded, processing",
       "rejected": "Not accepted",
-      "error": "Error"
+      "error": "Error",
+      "resume": "Waiting for the file to resume"
     }
   },
   "server_settings": {