fix(qdrant): reject empty vectors in upsert_points

Prevent Qdrant from rejecting entire batches when any point
has an empty vector. Log error with count before failing.

libs/agent/embed/qdrant.rs

@@ -89,6 +89,16 @@ impl QdrantClient {
             return Ok(());
         }
 
+        // Reject empty vectors — they cause Qdrant to reject the entire batch
+        let empty_vectors = points.iter().filter(|p| p.vector.is_empty()).count();
+        if empty_vectors > 0 {
+            tracing::error!(empty_count = empty_vectors, total = points.len(), "upsert_points: REJECTING points with empty vectors");
+            return Err(crate::AgentError::Qdrant(format!(
+                "refusing to upsert {} points with empty vectors",
+                empty_vectors
+            )));
+        }
+
         let collection_name = Self::collection_name(&points[0].payload.entity_type);
         self.upsert_to_collection(&collection_name, points).await
     }