feat(bulk): SuggestionService.for_selection consensus + POST /api/suggestions/bulk

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/api/suggestions.py

@@ -85,3 +85,35 @@ async def dismiss_suggestion(image_id: int):
         await AllowlistService(session).dismiss(image_id, body["tag_id"])
         await session.commit()
     return "", 204
+
+
+@suggestions_bp.route("/suggestions/bulk", methods=["POST"])
+async def bulk_suggestions():
+    body = await request.get_json()
+    if not body or "image_ids" not in body:
+        return jsonify({"error": "image_ids required"}), 400
+    raw = body["image_ids"]
+    if not isinstance(raw, list) or not raw:
+        return jsonify({"error": "image_ids must be a non-empty list"}), 400
+    try:
+        ids = [int(x) for x in raw]
+    except (TypeError, ValueError):
+        return jsonify({"error": "image_ids must be integers"}), 400
+    if len(ids) > 200:
+        return jsonify({"error": "selection too large (max 200)"}), 400
+    try:
+        threshold = float(body.get("threshold", 0.8))
+    except (TypeError, ValueError):
+        threshold = 0.8
+    threshold = min(1.0, max(0.0, threshold))
+    async with get_session() as session:
+        suggestions = await SuggestionService(session).for_selection(
+            ids, threshold=threshold
+        )
+    return jsonify(
+        {
+            "suggestions": suggestions,
+            "evaluated": len(ids),
+            "threshold": threshold,
+        }
+    )