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/stats.rs

@@ -523,9 +523,8 @@ mod tests {
         let mut stats = UsageStats::new();
         stats.session_start = Some(Instant::now());
 
-        // The duration should be at least 0 seconds
-        let duration = stats.get_session_duration();
-        assert!(duration >= 0);
+        // Verify duration is returned (u64 is always non-negative)
+        let _duration = stats.get_session_duration();
     }
 
     #[test]