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/extension_api/wit/since_v0.3.0/platform.wit

@@ -0,0 +1,24 @@
+interface platform {
+    /// An operating system.
+    enum os {
+        /// macOS.
+        mac,
+        /// Linux.
+        linux,
+        /// Windows.
+        windows,
+    }
+
+    /// A platform architecture.
+    enum architecture {
+        /// AArch64 (e.g., Apple Silicon).
+        aarch64,
+        /// x86.
+        x86,
+        /// x86-64.
+        x8664,
+    }
+
+    /// Gets the current operating system and architecture.
+    current-platform: func() -> tuple<os, architecture>;
+}