feat(tags): show a character's fandom on its chip (truncated)

A character chip with a fandom only rendered a bare arrow. Surface the fandom
NAME inline, truncated to 15 chars (full name in the tooltip). Resolve the name
via a Tag self-join in both tag paths the modal uses — list_for_image
(/api/images/<id>/tags) and gallery get_image_with_tags
(/api/gallery/image/<id>) — so chips show the fandom on first open and after any
reload. Falls back to the bare arrow when only fandom_id is known. Operator-asked
2026-06-09.

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

backend/app/services/gallery_service.py

@@ -558,13 +558,26 @@ class GalleryService:
         record = await self.session.get(ImageRecord, image_id)
         if record is None:
             return None
+        # Self-join Tag to resolve a character's fandom NAME (not just id) so the
+        # modal chip can label it without an N+1 — mirrors list_for_image.
+        fandom_alias = Tag.__table__.alias("fandom_lookup")
         tag_stmt = (
-            select(Tag)
-            .join(image_tag, image_tag.c.tag_id == Tag.id)
+            select(
+                Tag.id,
+                Tag.name,
+                Tag.kind,
+                Tag.fandom_id,
+                fandom_alias.c.name.label("fandom_name"),
+            )
+            .select_from(
+                Tag.__table__
+                .join(image_tag, image_tag.c.tag_id == Tag.id)
+                .outerjoin(fandom_alias, Tag.fandom_id == fandom_alias.c.id)
+            )
             .where(image_tag.c.image_record_id == image_id)
             .order_by(Tag.kind.asc(), Tag.name.asc())
         )
-        tags = (await self.session.execute(tag_stmt)).scalars().all()
+        tags = (await self.session.execute(tag_stmt)).all()
         # Fetch the canonical post.post_date for this image (if any) so
         # the modal can show "Posted on <date>" alongside import date.
         posted_at = None
@@ -608,6 +621,7 @@ class GalleryService:
                     "name": t.name,
                     "kind": t.kind.value if hasattr(t.kind, "value") else t.kind,
                     "fandom_id": t.fandom_id,
+                    "fandom_name": t.fandom_name,
                 }
                 for t in tags
             ],