fix: await ensure_collection and survive partial embed failures in document sync

- ensure_collection was called without await, so the coroutine never ran
  and fresh tenants had no collection when the upsert hit Qdrant
- a single None entry from embed_batch poisoned the point batch and
  aborted the whole document upsert; failed chunks are now skipped with
  a warning (all-failed raises and the IndexResult reports failure)
- raw client.delete/client.upsert calls now go through the async wrapper
  (delete_by_filter and the new batch upsert_points method)

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

src/services/document_sync_service.py

@@ -194,19 +194,15 @@ class DocumentSyncService:
     ) -> int:
         """Create vector embeddings for document content."""
         collection = get_qdrant_collection_name(user)
-        self.qdrant.ensure_collection(collection)
+        await self.qdrant.ensure_collection(collection)
 
-        # Delete existing chunks for this document
+        # Delete existing chunks for this document (via the async wrapper)
         try:
-            await self.qdrant.client.delete(
+            await self.qdrant.delete_by_filter(
                 collection_name=collection,
-                points_selector={
-                    "filter": {
-                        "must": [
-                            {"key": "doc_type", "match": {"value": "document"}},
-                            {"key": "paperless_id", "match": {"value": document_id}},
-                        ]
-                    }
+                filter_conditions={
+                    "doc_type": "document",
+                    "paperless_id": document_id,
                 }
             )
         except Exception as e:
@@ -217,12 +213,22 @@ class DocumentSyncService:
         if not chunks:
             return 0
 
-        # Generate embeddings
+        # Generate embeddings (embed_batch returns None for failed chunks)
         embeddings = await self.ollama.embed_batch(chunks)
 
-        # Build points
+        # Build points, skipping chunks whose embedding failed. Previously a
+        # single None embedding poisoned the batch and aborted the whole
+        # document upsert.
         points = []
+        skipped = 0
         for i, (chunk, embedding) in enumerate(zip(chunks, embeddings)):
+            if embedding is None:
+                skipped += 1
+                logger.warning(
+                    f"Skipping chunk {i} of document {document_id}: embedding failed"
+                )
+                continue
+
             point_id = str(uuid.uuid4())
             content_hash = hashlib.md5(chunk.encode()).hexdigest()
 
@@ -240,9 +246,19 @@ class DocumentSyncService:
                 }
             })
 
-        # Upsert to Qdrant
+        if skipped and not points:
+            raise RuntimeError(
+                f"All {skipped} chunk embeddings failed for document {document_id}"
+            )
+        if skipped:
+            logger.warning(
+                f"Document {document_id}: {skipped}/{len(chunks)} chunks skipped "
+                f"(embedding failures); indexing the remaining {len(points)}"
+            )
+
+        # Upsert to Qdrant in one batch via the async wrapper
         if points:
-            await self.qdrant.client.upsert(
+            await self.qdrant.upsert_points(
                 collection_name=collection,
                 points=points
             )