style: fix strict clippy and TypeScript type errors

- Fix assertions on constants in clipboard.rs (use const blocks)
- Fix unnecessary unwrap after is_ok check in git.rs
- Remove redundant u64 >= 0 comparison in stats.rs
- Add #[allow(clippy::useless_vec)] to sorting tests
- Add missing beforeEach import to vitest.setup.ts
- Change global.Audio to globalThis.Audio in notifications.test.ts
- Add type annotations to fix null type narrowing in conversations.test.ts

src-tauri/src/sessions.rs

@@ -321,6 +321,7 @@ mod tests {
     }
 
     #[test]
+    #[allow(clippy::useless_vec)]
     fn test_session_sorting_by_activity() {
         let old_time = Utc.with_ymd_and_hms(2024, 1, 1, 0, 0, 0).unwrap();
         let new_time = Utc.with_ymd_and_hms(2024, 6, 15, 12, 0, 0).unwrap();