feat(library): edit/fix album metadata

Correct an owned album's artist/album/year from the Library modal ("Edit
metadata"). PATCH /api/library/[id] renames the folder to the canonical
Artist/Album (Year) scheme on the /music mount, updates the LibraryItem,
and re-resolves the MusicBrainz release-group (cover art) when the
artist/album changed (best-effort — keeps the old rgMbid on an MB outage).

- New shared lib/library-path.ts (safeName, albumDir, yearFromPath); the
  manual-import route now uses it so edits and imports name folders
  identically.
- Library GET falls back to the folder's "(YYYY)" for the year when there's
  no matching release, so edited/manual years show in the grid.
- Does NOT rewrite embedded file tags (a worker/mutagen job) — Lyra reads
  from the folder + DB. Guards paths inside the library root; 409 on folder
  or (artist,album) collision.

web 172 tests.

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

web/src/app/library/library-client.tsx

@@ -40,10 +40,46 @@ export function LibraryClient() {
   const [sort, setSort] = useState<SortKey>("added");
   const [open, setOpen] = useState<Album | null>(null);
   const [confirmDelete, setConfirmDelete] = useState(false);
+  const [editing, setEditing] = useState(false);
+  const [edit, setEdit] = useState({ artist: "", album: "", year: "" });
+  const [saving, setSaving] = useState(false);
 
   function show(a: Album | null) {
     setOpen(a);
     setConfirmDelete(false);
+    setEditing(false);
+  }
+
+  function startEdit() {
+    if (!open) return;
+    setEdit({ artist: open.artist, album: open.album, year: open.year ?? "" });
+    setEditing(true);
+  }
+
+  async function saveEdit() {
+    if (!open) return;
+    if (!edit.artist.trim() || !edit.album.trim()) {
+      toast("Artist and album are required");
+      return;
+    }
+    setSaving(true);
+    try {
+      const res = await fetch(`/api/library/${open.id}`, {
+        method: "PATCH",
+        headers: { "content-type": "application/json" },
+        body: JSON.stringify({ artist: edit.artist.trim(), album: edit.album.trim(), year: edit.year.trim() }),
+      }).catch(() => null);
+      if (res?.ok) {
+        toast(`Updated ${edit.album.trim()}`);
+        setEditing(false);
+        show(null);
+        refresh();
+      } else {
+        toast((res && (await res.json().catch(() => null))?.error) || "Couldn't update album");
+      }
+    } finally {
+      setSaving(false);
+    }
   }
 
   async function remove() {
@@ -173,7 +209,31 @@ export function LibraryClient() {
           album={{ rgMbid: open.rgMbid, album: open.album, artist: open.artist, year: open.year, type: open.primaryType, artistMbid: open.artistMbid, trackNames: open.trackNames }}
           status={<span className="chip done">In library · {open.format}</span>}
           actions={
-            confirmDelete ? (
+            editing ? (
+              <div className="edit-meta">
+                <label className="field">
+                  <span>Artist</span>
+                  <input aria-label="edit artist" value={edit.artist} onChange={(e) => setEdit((s) => ({ ...s, artist: e.target.value }))} />
+                </label>
+                <label className="field">
+                  <span>Album</span>
+                  <input aria-label="edit album" value={edit.album} onChange={(e) => setEdit((s) => ({ ...s, album: e.target.value }))} />
+                </label>
+                <label className="field">
+                  <span>Year</span>
+                  <input aria-label="edit year" placeholder="YYYY" value={edit.year} onChange={(e) => setEdit((s) => ({ ...s, year: e.target.value }))} />
+                </label>
+                <div className="save-row">
+                  <button className="btn sm accent" onClick={saveEdit} disabled={saving}>
+                    {saving ? "Saving…" : "Save"}
+                  </button>
+                  <button className="btn sm ghost" onClick={() => setEditing(false)} disabled={saving}>
+                    Cancel
+                  </button>
+                </div>
+                <p className="muted-note">Renames the folder on disk and re-resolves cover art. Embedded file tags are left as-is.</p>
+              </div>
+            ) : confirmDelete ? (
               <>
                 <span className="rmeta">Delete this album and its files from disk?</span>
                 <button className="btn sm accent" onClick={remove}>
@@ -184,9 +244,14 @@ export function LibraryClient() {
                 </button>
               </>
             ) : (
-              <button className="btn sm ghost" onClick={() => setConfirmDelete(true)}>
-                Delete album
-              </button>
+              <>
+                <button className="btn sm ghost" onClick={startEdit}>
+                  Edit metadata
+                </button>
+                <button className="btn sm ghost" onClick={() => setConfirmDelete(true)}>
+                  Delete album
+                </button>
+              </>
             )
           }
         />