Bugfix: drop redundant std::time:: qualifier in accent_color_linux test

Linux clippy is stricter on `unused_qualifications` (the module is `#[cfg(target_os = "linux")]`, so macOS never sees this code) and tripped on `std::time::Duration::from_secs(2)` since `Duration` is already imported at the top of the file. Use the bare `Duration::from_secs(2)`.

Caught by CI on the previous push (commit 91afacb); verified locally on the UTM Ubuntu VM with `cargo clippy --all-targets --locked -- -D warnings`.

Author: vdavid

apps/desktop/src-tauri/src/accent_color_linux.rs

@@ -244,7 +244,7 @@ mod tests {
         let elapsed = start.elapsed();
 
         assert!(
-            elapsed < std::time::Duration::from_secs(2),
+            elapsed < Duration::from_secs(2),
             "read_accent_color took {elapsed:?}, expected < 2 s (PROBE_TIMEOUT={PROBE_TIMEOUT:?})",
         );
         assert!(color.starts_with('#'), "expected #rrggbb, got {color}");