Add refresh from source for entries and whole lists

- Every provider can look an entry up again by its ID (TMDB, TheTVDB,
  IGDB, Deezer, MusicBrainz, Wikipedia); search and lookup share parsing
- POST /api/items/{id}/refresh re-applies title, subtitle, year,
  description, link, details and artwork. Kept: the "why" note, rank,
  theater production/venue/cast and a theater entry's year, the Deezer
  preview match. Empty source fields don't erase existing values
- New items.image_custom column (migration 4; existing uploads marked)
  records artwork the owner chose; refresh keeps it unless asked
- Refused for custom lists and hand-added entries; entries the source
  dropped are reported, and a refresh whose title shares no words with
  the current one is rejected as a likely bad ID
- Editor: refresh button per row (asks about the owner's own artwork),
  and "Refresh all" with a confirm step, replace-my-art checkbox,
  progress with Stop, and a summary of problems

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

web/static/css/app.css

@@ -692,6 +692,11 @@ input[type="checkbox"] { accent-color: var(--accent); width: 18px; height: 18px;
 .art-edit-actions .row-btns { display: flex; gap: 6px; flex-wrap: wrap; }
 @media (max-width: 480px) { .art-edit { grid-template-columns: 80px 1fr; } .art-edit .result-art { width: 80px; } }
 
+.refresh-art-choice { align-items: flex-start; padding: 12px 14px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg); }
+.refresh-art-choice input { margin-top: 2px; }
+.refresh-failures { margin: 0; padding-left: 18px; font-size: 13.5px; color: var(--muted); display: flex; flex-direction: column; gap: 4px; max-height: 240px; overflow-y: auto; }
+.refresh-failures b { color: var(--text); font-weight: 600; }
+
 /* settings */
 .settings { display: grid; grid-template-columns: 200px 1fr; gap: 32px; align-items: start; }
 .settings-nav { position: sticky; top: 80px; display: flex; flex-direction: column; gap: 2px; }