fix: frame_number is BIGINT in DB, use i64 not i32

frame_number column in face_detections table is defined as BIGINT (INT8).
Using i32 caused sqlx type mismatch at runtime. Fixed in:
- identity_agent_api.rs: query_as tuples and HashMap key
- qdrant_db.rs: upsert_face_embedding signature and row extraction

src/core/db/qdrant_db.rs

@@ -758,7 +758,7 @@ impl QdrantDb {
         vector: &[f32],
         file_uuid: &str,
         trace_id: i32,
-        frame_number: i32,
+        frame_number: i64,
     ) -> Result<()> {
         let url = format!(
             "{}/collections/{}/points?wait=true",
@@ -889,7 +889,7 @@ pub async fn sync_face_embeddings(file_uuid: &str) -> Result<()> {
     for row in &rows {
         let id: i32 = row.get(0);
         let trace_id: Option<i32> = row.get(1);
-        let frame_number: i32 = row.get(2);
+        let frame_number: i64 = row.get(2);
         let embedding: Option<Vec<f32>> = row.get(3);
 
         if let (Some(emb), Some(tid)) = (embedding, trace_id) {