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>

flake.nix

@@ -0,0 +1,41 @@
+{
+  description = "Zed is a minimal code editor crafted for speed and collaboration with humans and AI.";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    crane.url = "github:ipetkov/crane";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs =
+    inputs@{ flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = [
+        "x86_64-linux"
+        "x86_64-darwin"
+        "aarch64-linux"
+        "aarch64-darwin"
+      ];
+
+      imports = [
+        ./nix/modules/overlays.nix
+        ./nix/modules/packages.nix
+        ./nix/modules/partitions.nix
+      ];
+    };
+
+  nixConfig = {
+    extra-substituters = [
+      "https://zed.cachix.org"
+      "https://cache.garnix.io"
+    ];
+    extra-trusted-public-keys = [
+      "zed.cachix.org-1:/pHQ6dpMsAZk2DiP4WCL0p9YDNKWj2Q5FL20bNmw1cU="
+      "cache.garnix.io:CTFPyKSLcx5RMJKfLo5EEPUObbA78b0YQ2DTCJXqr9g="
+    ];
+  };
+}