feat: API key routes, search endpoint, conversation type wiring

- GET/POST/DELETE /api/api-keys blueprint registered
- GET /api/search?q=&content_type=&limit= semantic search endpoint
- create_conversation gains conversation_type param (default "chat")
- cleanup_old_conversations excludes mcp type from retention sweep
- POST /api/chat/conversations accepts conversation_type body field

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/fabledassistant/routes/search.py

@@ -0,0 +1,46 @@
+from quart import Blueprint, jsonify, request
+
+from fabledassistant.auth import login_required, get_current_user_id
+from fabledassistant.services.embeddings import semantic_search_notes
+
+search_bp = Blueprint("search", __name__, url_prefix="/api/search")
+
+
+def _content_type_to_is_task(content_type: str) -> bool | None:
+    """Map content_type query param to semantic_search_notes is_task arg."""
+    if content_type == "note":
+        return False
+    if content_type == "task":
+        return True
+    return None  # "all" or unknown → no filter
+
+
+@search_bp.route("", methods=["GET"])
+@login_required
+async def search_route():
+    uid = get_current_user_id()
+    q = (request.args.get("q") or "").strip()
+    if not q:
+        return jsonify({"error": "q is required"}), 400
+
+    content_type = request.args.get("content_type", "all")
+    limit = min(request.args.get("limit", 10, type=int), 50)
+    is_task = _content_type_to_is_task(content_type)
+
+    results = await semantic_search_notes(
+        uid, q, limit=limit, is_task=is_task, threshold=0.3
+    )
+    return jsonify({
+        "results": [
+            {
+                "id": note.id,
+                "title": note.title,
+                "body": note.body or "",
+                "is_task": note.is_task,
+                "tags": note.tags or [],
+                "similarity": score,
+            }
+            for score, note in results  # semantic_search_notes returns list[tuple[float, Note]]
+        ],
+        "total": len(results),
+    })