perf: switch Qdrant to AsyncQdrantClient with explicit timeout

Every vector call ran on the sync QdrantClient inside async wrapper
methods, blocking the FastAPI event loop per Qdrant round-trip. The
wrapper now holds an AsyncQdrantClient (timeout via QDRANT_TIMEOUT,
default 30s) and awaits all client calls; the wrapper API is unchanged.

Call sites off the wrapper were fixed too: the HybridRAG document leg
now uses the async search_vectors wrapper instead of the deprecated raw
client.search (also fixing its call to the nonexistent ollama.embed_text
which made the leg permanently report 'failed'), the health check awaits
get_collections, and document_sync's raw delete/upsert calls are awaited
(routed through wrappers in the next commit).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QbFZyDvYksazX6nYQYZ67L

src/core/dependencies.py

@@ -101,7 +101,8 @@ def get_qdrant_client() -> QdrantClientWrapper:
     settings = get_settings()
     client = QdrantClientWrapper(
         url=settings.qdrant_url,
-        embedding_dim=768  # nomic-embed-text default
+        embedding_dim=768,  # nomic-embed-text default
+        timeout=settings.qdrant_timeout
     )
     logger.debug("Created Qdrant client instance")
     return client
@@ -591,7 +592,7 @@ async def check_service_health() -> dict:
     try:
         qdrant = get_qdrant_client()
         # Check if we can list collections
-        collections = qdrant.client.get_collections()
+        await qdrant.client.get_collections()
         health["qdrant"] = True
     except Exception as e:
         logger.error(f"Qdrant health check failed: {e}")