feat(suggestions): user-managed blocklist for noisy auto-tags

Adds a tag_suggestion_blocklist table + service-layer filter so the
user can permanently suppress specific canonical tag names from the
suggestion stream (WD14 anatomy/composition tags like '1girl',
'breasts', 'nipples' that aren't useful for the discoverability use
case this app targets).

Data model
  - migration k26042201: tag_suggestion_blocklist(name TEXT PK, created_at)
  - model TagSuggestionBlocklistEntry

Service
  - tag_suggestions._blocklisted_names() snapshots the current set
  - get_suggestions filters merged results before grouping, so both
    WD14- and embedding-sourced suggestions respect the blocklist
  - get_bulk_suggestions inherits the filter via its per-image call
    to get_suggestions

API
  - GET  /api/suggestions/blocklist           -> {ok, names}
  - POST /api/suggestions/blocklist           -> add one
  - POST /api/suggestions/blocklist/delete    -> remove one
  - POST /api/suggestions/blocklist/bulk      -> replace the whole list
    (backs the settings textarea save button)

UI
  - modal suggestion chip gets a third action button (⊘) alongside
    accept (✓) / reject (✕). Clicking it adds the name to the
    blocklist, logs a rejection for ML feedback on this image, and
    sweeps every chip on the page carrying that same name.
  - Settings -> Maintenance -> Suggestion blocklist section with a
    monospaced textarea (one name per line) + Save. Loads current
    entries on mount.

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

app/main.py

@@ -936,6 +936,68 @@ def reject_image_suggestion(image_id):
     return jsonify({'ok': True})
 
 
+# ---------------------------
+# Suggestion blocklist — user-managed list of canonical tag names that
+# should never appear as auto-suggestions (e.g. noisy WD14 anatomy tags).
+# ---------------------------
+
+@main.get("/api/suggestions/blocklist")
+def list_suggestion_blocklist():
+    from app.models import TagSuggestionBlocklistEntry
+    rows = (
+        TagSuggestionBlocklistEntry.query
+        .order_by(TagSuggestionBlocklistEntry.name)
+        .all()
+    )
+    return jsonify(ok=True, names=[r.name for r in rows])
+
+
+@main.post("/api/suggestions/blocklist")
+def add_suggestion_blocklist():
+    from app.models import TagSuggestionBlocklistEntry
+    payload = request.get_json(force=True, silent=True) or {}
+    name = (payload.get('name') or '').strip()
+    if not name:
+        return jsonify(ok=False, error='missing_name'), 400
+    existing = TagSuggestionBlocklistEntry.query.get(name)
+    if existing is not None:
+        return jsonify(ok=True, added=False, name=name)
+    db.session.add(TagSuggestionBlocklistEntry(name=name))
+    db.session.commit()
+    return jsonify(ok=True, added=True, name=name)
+
+
+@main.post("/api/suggestions/blocklist/delete")
+def remove_suggestion_blocklist():
+    from app.models import TagSuggestionBlocklistEntry
+    payload = request.get_json(force=True, silent=True) or {}
+    name = (payload.get('name') or '').strip()
+    if not name:
+        return jsonify(ok=False, error='missing_name'), 400
+    existing = TagSuggestionBlocklistEntry.query.get(name)
+    if existing is not None:
+        db.session.delete(existing)
+        db.session.commit()
+        return jsonify(ok=True, removed=True, name=name)
+    return jsonify(ok=True, removed=False, name=name)
+
+
+@main.post("/api/suggestions/blocklist/bulk")
+def bulk_replace_suggestion_blocklist():
+    """Replace the entire blocklist with the provided names. Textarea-save path."""
+    from app.models import TagSuggestionBlocklistEntry
+    payload = request.get_json(force=True, silent=True) or {}
+    names = payload.get('names', [])
+    if not isinstance(names, list):
+        return jsonify(ok=False, error='names_must_be_list'), 400
+    cleaned = sorted({str(n).strip() for n in names if str(n) and str(n).strip()})
+    TagSuggestionBlocklistEntry.query.delete()
+    for name in cleaned:
+        db.session.add(TagSuggestionBlocklistEntry(name=name))
+    db.session.commit()
+    return jsonify(ok=True, count=len(cleaned), names=cleaned)
+
+
 @main.post("/image/<int:image_id>/tags/add")
 def add_tag(image_id):
     """