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_v0.5.0/slash-command.wit

@@ -0,0 +1,41 @@
+interface slash-command {
+    use common.{range};
+
+    /// A slash command for use in the Assistant.
+    record slash-command {
+        /// The name of the slash command.
+        name: string,
+        /// The description of the slash command.
+        description: string,
+        /// The tooltip text to display for the run button.
+        tooltip-text: string,
+        /// Whether this slash command requires an argument.
+        requires-argument: bool,
+    }
+
+    /// The output of a slash command.
+    record slash-command-output {
+        /// The text produced by the slash command.
+        text: string,
+        /// The list of sections to show in the slash command placeholder.
+        sections: list<slash-command-output-section>,
+    }
+
+    /// A section in the slash command output.
+    record slash-command-output-section {
+        /// The range this section occupies.
+        range: range,
+        /// The label to display in the placeholder for this section.
+        label: string,
+    }
+
+    /// A completion for a slash command argument.
+    record slash-command-argument-completion {
+        /// The label to display for this completion.
+        label: string,
+        /// The new text that should be inserted into the command when this completion is accepted.
+        new-text: string,
+        /// Whether the command should be run when accepting this completion.
+        run-command: bool,
+    }
+}