feat: update core API, database layer, and worker modules

- Remove unused imports (n8n_search, universal_search, Client, Arc, etc.)
- Update API endpoints for identity, face recognition, search
- Fix postgres_db.rs search_videos parent_uuid column
- Add snapshot API and identity agent API
- Clean up backup files (.bak, .bak2)

src/bin/test_bm25_simple.rs

@@ -31,7 +31,7 @@ async fn main() -> Result<()> {
         );
 
         // 顯示轉換後的 tsquery (除錯用)
-        match pg.prepare_tsquery(query_str) {
+        match pg.prepare_tsquery(query_str).await {
             Ok(tsquery) => println!("  TSQUERY: {}", tsquery),
             Err(e) => println!("  TSQUERY 錯誤: {}", e),
         }

src/bin/test_simplified_chinese.rs

@@ -20,7 +20,7 @@ async fn main() -> Result<()> {
         println!("\n🔍 測試查詢 (簡體): '{}'", query_str);
 
         // 顯示轉換後的 tsquery
-        match pg.prepare_tsquery(query_str) {
+        match pg.prepare_tsquery(query_str).await {
             Ok(tsquery) => println!("  TSQUERY: {}", tsquery),
             Err(e) => println!("  TSQUERY 錯誤: {}", e),
         }

src/bin/test_synonym_expansion.rs

@@ -39,7 +39,7 @@ async fn main() -> Result<()> {
         }
 
         // 顯示轉換後的 tsquery
-        match pg.prepare_tsquery(query_str) {
+        match pg.prepare_tsquery(query_str).await {
             Ok(tsquery) => println!("  TSQUERY: {}", tsquery),
             Err(e) => println!("  TSQUERY 錯誤: {}", e),
         }