feat: Phase 2-3 TKG-only architecture

Phase 2.1: build_face_trace_nodes_from_qdrant()
- Read trace_id, frame, bbox directly from Qdrant payload
- No dependency on face_detections table

Phase 2.3: Rule2 queries TKG nodes
- identity resolution from tkg_nodes.properties.identity_id
- TKG-only architecture (Phase 2.3)

Phase 3: Identity Agent updates TKG nodes
- match_faces_iterative() updates tkg_nodes.properties
- bind_identity_trace() syncs identity_id to TKG
- unbind_identity() removes identity_id from TKG

Test results:
- 23 face_trace nodes from Qdrant (Phase 2.1)
- 75 relationship chunks (Rule2)
- TKG rebuild: Phase0 → Phase1 → Phase2

src/api/identity_binding.rs

@@ -225,6 +225,32 @@ pub async fn unbind_identity(
         )
     })?;
 
+    // Phase 2.3: Also update TKG node (find trace_id first)
+    let trace_id_opt: Option<i32> = sqlx::query_scalar(&format!(
+        "SELECT trace_id FROM {} WHERE file_uuid = $1 AND face_id = $2",
+        table
+    ))
+    .bind(&req.file_uuid)
+    .bind(&req.face_id)
+    .fetch_optional(state.db.pool())
+    .await
+    .ok()
+    .flatten();
+
+    if let Some(trace_id) = trace_id_opt {
+        let nodes_table = crate::core::db::schema::table_name("tkg_nodes");
+        let external_id = format!("trace_{}", trace_id);
+        let _ = sqlx::query(&format!(
+            "UPDATE {} SET properties = properties - 'identity_id' - 'identity_name' \
+             WHERE file_uuid = $1 AND node_type = 'face_trace' AND external_id = $2",
+            nodes_table
+        ))
+        .bind(&req.file_uuid)
+        .bind(&external_id)
+        .execute(state.db.pool())
+        .await;
+    }
+
     // Record history if there was a binding
     if let Some(identity_id) = old_identity_id {
         // Clear bind redo stack
@@ -794,6 +820,33 @@ pub async fn bind_identity_trace(
         )
     })?;
 
+// Phase 2.3: Also update TKG node properties
+    let nodes_table = crate::core::db::schema::table_name("tkg_nodes");
+    let external_id = format!("trace_{}", req.trace_id);
+    let identity_name: Option<String> = sqlx::query_scalar(&format!(
+        "SELECT name FROM {} WHERE id = $1",
+        id_table
+    ))
+    .bind(identity_id)
+    .fetch_optional(state.db.pool())
+    .await
+    .ok()
+    .flatten();
+
+    let _ = sqlx::query(&format!(
+        "UPDATE {} SET properties = jsonb_set(\
+            jsonb_set(properties, '{{identity_id}}', $1::jsonb, false),\
+            '{{identity_name}}', $2::jsonb, false)\
+         WHERE file_uuid = $3 AND node_type = 'face_trace' AND external_id = $4",
+        nodes_table
+    ))
+    .bind(identity_id)
+    .bind(identity_name.as_deref())
+    .bind(&req.file_uuid)
+    .bind(&external_id)
+    .execute(state.db.pool())
+    .await;
+
     // Clear bind redo stack
     let _ = sqlx::query(&format!(
         "DELETE FROM {} WHERE identity_id = $1 AND is_undone = true AND operation IN ('bind','unbind','bind_trace')",