fix: clear thumbnail cache and temp dirs on new session

Co-authored-by: Cursor <cursoragent@cursor.com>

src-tauri/src/lib.rs

@@ -19,6 +19,7 @@ pub fn run() {
             media_analysis::extract_keyframes,
             media_analysis::extract_waveform,
             media_analysis::extract_thumbnails,
+            media_analysis::cleanup_thumbnails,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");