logiguard fork: GPUI xdg-activation keyboard-focus serial fix

Single-commit orphan branch: full zed-industries/zed @ 8c74db0 source tree
with a 3-file patch applied (no upstream history).

Patch (crates/gpui_linux/src/linux/wayland/):
  - serial.rs: add SerialKind::KeyboardEnter
  - client.rs: store wl_keyboard.enter serial; add latest_serial_of()
  - window.rs: activate() uses keyboard-enter serial (Mutter focus gate)

Mutter honors window activation only when the token carries the keyboard-
focus serial from wl_keyboard.enter; GPUI used a stale mouse-press serial.
See docs/tray-window-focus-wayland.md in logiguard.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/fs_benchmarks/src/main.rs

@@ -0,0 +1,34 @@
+use fs::Fs;
+use gpui::AppContext;
+use gpui_platform::headless;
+
+fn main() {
+    let Some(path_to_read) = std::env::args().nth(1) else {
+        println!("Expected path to read as 1st argument.");
+        return;
+    };
+
+    let _ = headless().run(|cx| {
+        let fs = fs::RealFs::new(None, cx.background_executor().clone());
+        cx.background_spawn(async move {
+            let timer = std::time::Instant::now();
+            let result = fs.load_bytes(path_to_read.as_ref()).await;
+            let elapsed = timer.elapsed();
+            if let Err(e) = result {
+                println!("Failed `load_bytes` after {elapsed:?} with error `{e}`");
+            } else {
+                println!("Took {elapsed:?} to read {} bytes", result.unwrap().len());
+            };
+            let timer = std::time::Instant::now();
+            let result = fs.metadata(path_to_read.as_ref()).await;
+            let elapsed = timer.elapsed();
+            if let Err(e) = result {
+                println!("Failed `metadata` after {elapsed:?} with error `{e}`");
+            } else {
+                println!("Took {elapsed:?} to query metadata");
+            };
+            std::process::exit(0);
+        })
+        .detach();
+    });
+}