fix(suggestions): parse (Fandom) suffix on accept + heal legacy rows

Two-part fix for the reported bug where accepting a character
suggestion named 'Jinx (League Of Legends)' created a single
malformed character tag with fandom_id=NULL and the whole suffix
embedded in the name, and never attached the fandom tag to the
image.

Root cause: WD14 predictions store names like
'jinx_(league_of_legends)'. app.services.tag_suggestions
._canonicalize_wd14_name transforms that to 'Jinx (League Of
Legends)' for character/copyright categories. The suggestion chip
renders that canonicalized string. On ✓, accept_image_suggestion
looked for an existing character with name = 'Jinx (League Of
Legends)' — post-refactor no such row exists (names are bare) —
fell into the 0-candidate branch, and created a fresh malformed
character.

Going forward (main.py):
  accept_image_suggestion's character branch now splits a
  '(Fandom)' suffix off the incoming name before the 0/1/N lookup.
  If it splits, find-or-create the fandom tag, then find-or-create
  a character with (kind='character', name=bare, fandom_id=<f>).
  If no suffix, unchanged 0/1/N behavior.

Backfill for already-corrupted rows (tasks/maintenance.py):
  New _heal_malformed_character_names pass runs before the
  existing sync-fandoms-to-images logic. Finds
  (kind='character', fandom_id IS NULL, name LIKE '% (%)%'),
  parses the suffix via the same regex, and either promotes the
  row to (name=bare, fandom_id=<f>) or merges into an existing
  canonical character. tag_reference_embedding rows (string PK)
  are cascade-renamed alongside. Same auto-merge semantics as
  migration j26042101 Phase 2.

Implementation is all raw SQL to sidestep an ORM autoflush
ordering quirk: ORM-level fandom INSERT + subsequent tag UPDATE
referencing its fresh id hit a transient FK violation in worker
task context. Raw SQL with an explicit commit after fandom
insert avoids the ambiguity.

Verified locally:
  - Fresh accept of 'CanonicalChar (Canonical Fandom)' against a
    pre-existing canonical character: resolved to the canonical
    row, fandom attached to image.
  - Seeded malformed 'LegacyJinx (League Of Legends)' character
    with fandom_id=NULL attached to an image: sync task healed it
    to bare 'LegacyJinx' + fandom_id, attached the fandom row to
    image_tags, final counts {healed:1, skipped:0,
    links_added:1}.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/main.py

@@ -872,27 +872,52 @@ def accept_image_suggestion(image_id):
         if tag is None:
             return jsonify(ok=False, error="tag_not_found"), 404
     elif kind == "character":
-        candidates = Tag.query.filter_by(kind="character", name=name).all()
-        if len(candidates) == 1:
-            tag = candidates[0]
-        elif len(candidates) == 0:
-            tag = Tag(kind="character", name=name, fandom_id=None)
-            db.session.add(tag)
-            db.session.flush()
+        # WD14 emits character names in 'bare_(fandom)' form. After canonical
+        # case/underscore handling the incoming name may look like
+        # 'Soraka (League Of Legends)'. Before the post-refactor 0/1/N
+        # lookup, split the '(Fandom)' suffix and resolve the fandom to a
+        # fandom_id — otherwise the lookup misses every existing bare-name
+        # character and we'd create a new character whose entire name is
+        # 'Soraka (League Of Legends)' with fandom_id=NULL.
+        import re
+        fandom_suffix_match = re.match(r'^(.+?) \(([^()]+)\)$', name)
+        if fandom_suffix_match:
+            bare_name = fandom_suffix_match.group(1).strip()
+            suffix_fandom_name = fandom_suffix_match.group(2).strip()
+            f_tag = _ensure_fandom_tag(suffix_fandom_name)
+            candidates = (
+                Tag.query
+                .filter_by(kind="character", name=bare_name, fandom_id=f_tag.id)
+                .all()
+            )
+            if len(candidates) == 1:
+                tag = candidates[0]
+            else:
+                tag = Tag(kind="character", name=bare_name, fandom_id=f_tag.id)
+                db.session.add(tag)
+                db.session.flush()
         else:
-            return jsonify(
-                ok=False,
-                error="ambiguous",
-                candidates=[
-                    {
-                        "id": c.id,
-                        "display_name": c.display_name,
-                        "fandom_id": c.fandom_id,
-                        "fandom_name": c.fandom.name if c.fandom else None,
-                    }
-                    for c in candidates
-                ],
-            ), 409
+            candidates = Tag.query.filter_by(kind="character", name=name).all()
+            if len(candidates) == 1:
+                tag = candidates[0]
+            elif len(candidates) == 0:
+                tag = Tag(kind="character", name=name, fandom_id=None)
+                db.session.add(tag)
+                db.session.flush()
+            else:
+                return jsonify(
+                    ok=False,
+                    error="ambiguous",
+                    candidates=[
+                        {
+                            "id": c.id,
+                            "display_name": c.display_name,
+                            "fandom_id": c.fandom_id,
+                            "fandom_name": c.fandom.name if c.fandom else None,
+                        }
+                        for c in candidates
+                    ],
+                ), 409
     else:
         effective_kind = kind if kind else "user"
         tag = Tag.query.filter_by(kind=effective_kind, name=name).first()