Save source descriptions, add "Why it's #N", fix IGDB studio names

Descriptions
- Items keep the source's description (TMDB/TheTVDB overview, IGDB
  summary, Wikipedia intro) in a new items.description column
  (migration 3); editable in the item form
- Deezer/MusicBrainz track counts and album names are now display-only
  hints, not saved as descriptions

Why it's #N
- The owner's note is presented as "Why it's #N" in the editor and the
  public detail view, above an "About" section with the description

IGDB developers
- IGDB credits internal divisions ("Nintendo EAD", "Nintendo EPD
  Production Group No. 8"). A developer whose name shares its first word
  with its parent company is credited to the parent ("Nintendo");
  independently named studios keep their name (Retro Studios, Naughty
  Dog, Landfall Games)
- Fall back to the publisher when IGDB lists no developer

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

internal/providers/music.go

@@ -105,7 +105,7 @@ func (d *deezer) Search(ctx context.Context, query string) ([]Result, error) {
 				r.Extra["type"] = strings.ToUpper(a.RecordType[:1]) + a.RecordType[1:]
 			}
 			if a.NbTracks > 0 {
-				r.Overview = fmt.Sprintf("%d tracks", a.NbTracks)
+				r.Hint = fmt.Sprintf("%d tracks", a.NbTracks)
 			}
 			out = append(out, r)
 		}
@@ -126,7 +126,7 @@ func (d *deezer) Search(ctx context.Context, query string) ([]Result, error) {
 			Subtitle:    t.Artist.Name,
 			ImageURL:    cover(t.Album),
 			ExternalURL: t.Link,
-			Overview:    "From " + t.Album.Title,
+			Hint:        "From " + t.Album.Title,
 			Extra:       map[string]string{"album": t.Album.Title},
 		})
 	}
@@ -267,7 +267,7 @@ func (m *musicbrainz) Search(ctx context.Context, query string) ([]Result, error
 			if i == 0 || rel.ReleaseGroup.PrimaryType == "Album" {
 				r.ImageURL = "https://coverartarchive.org/release-group/" + rel.ReleaseGroup.ID + "/front-500"
 				r.Extra["album"] = rel.Title
-				r.Overview = "From " + rel.Title
+				r.Hint = "From " + rel.Title
 				if rel.ReleaseGroup.PrimaryType == "Album" {
 					break
 				}