feat(aionui): Add AionUi AI cowork desktop app (v2.1.4)

Build AionUi from source using bun for dependency fetching and
electron-vite for TypeScript compilation. Native addons
(better-sqlite3, sharp) are compiled against nixpkgs node-gyp.

The package uses a fixed-output derivation for bun install,
electron-vite for the build, and wraps the result with nixpkgs
electron for a fully self-contained runtime.

Also includes desktop entry and icon generation.

packages/aionui/default.nix

@@ -0,0 +1,5 @@
+{
+  pkgs,
+  ...
+}:
+pkgs.callPackage ./package.nix { }