perf(tkg): batch INSERT for co_occurrence edges using QueryBuilder

- Collect edges in Vec first, then batch insert in chunks of 100
- Uses sqlx::query_builder::QueryBuilder for efficient batch INSERT
- Reduces SQL round-trips from O(edges) to O(edges/100)
- Maintains ON CONFLICT DO UPDATE semantics

src/core/processor/tkg.rs

@@ -1407,6 +1407,9 @@ async fn build_co_occurrence_edges_from_qdrant(
     let points = face_points;
 
     let mut edge_count = 0;
+    // Collect edges for batch insert
+    let mut edges_to_insert: Vec<(&str, i64, i64, &str, String)> = Vec::new();
+
     for face in points {
         let yolo_frame = match yolo.frames.get(&face.frame.to_string()) {
             Some(f) => f,
@@ -1440,35 +1443,34 @@ async fn build_co_occurrence_edges_from_qdrant(
                 "object_confidence": det.confidence,
             });
 
-            if let Err(e) = sqlx::query(&format!(
-                r#"
-                INSERT INTO {} (edge_type, source_node_id, target_node_id, file_uuid, properties)
-                VALUES ($1, $2, $3, $4, $5::jsonb)
-                ON CONFLICT (file_uuid, edge_type, source_node_id, target_node_id)
-                DO UPDATE SET properties = COALESCE(EXCLUDED.properties, tkg_edges.properties)
-                "#,
-                edges_table
-            ))
-            .bind("CO_OCCURS_WITH")
-            .bind(face_node_id)
-            .bind(obj_node_id)
-            .bind(file_uuid)
-            .bind(serde_json::to_string(&edge_props)?)
-            .execute(pool)
-            .await
-            {
-                tracing::warn!(
-                    "[TKG] Edge insert failed (trace={}, obj={}): {}",
-                    face.trace_id,
-                    det.class_name,
-                    e
-                );
-                continue;
+            edges_to_insert.push(("CO_OCCURS_WITH", face_node_id, obj_node_id, file_uuid, serde_json::to_string(&edge_props)?));
+        }
     }
 
-            edge_count += 1;
+    // Batch insert edges
+    let batch_size = 100;
+    for chunk in edges_to_insert.chunks(batch_size) {
+        let mut query = sqlx::query_builder::QueryBuilder::new(&format!(
+            "INSERT INTO {} (edge_type, source_node_id, target_node_id, file_uuid, properties) VALUES ",
+            edges_table
+        ));
+        for (i, (edge_type, src, tgt, uuid, props)) in chunk.iter().enumerate() {
+            if i > 0 {
+                query.push(", ");
             }
+            query.push("(")
+                .push_bind(*edge_type)
+                .push_bind(*src)
+                .push_bind(*tgt)
+                .push_bind(*uuid)
+                .push_bind(props)
+                .push("::jsonb)");
         }
+        query.push(" ON CONFLICT (file_uuid, edge_type, source_node_id, target_node_id) DO UPDATE SET properties = COALESCE(EXCLUDED.properties, tkg_edges.properties)");
+        query.build().execute(pool).await?;
+    }
+
+    edge_count = edges_to_insert.len();
 
     Ok(edge_count)
 }