feat(desktop): Electron shell M2 — embedded server, desktop login, instance lock (#173)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/server/tsup.config.ts

@@ -1,8 +1,9 @@
 import { defineConfig } from "tsup";
 
 export default defineConfig({
-  // Explicitly name entries to preserve the dist/api/types.js subpath (exports "./api" points to it).
-  entry: { index: "src/index.ts", "api/types": "src/api/types.ts" },
+  // Explicitly name entries to preserve the dist/api/types.js and dist/lock.js subpaths
+  // (exports "./api" and "./lock" point to them; lock is side-effect-free for pre-checks).
+  entry: { index: "src/index.ts", "api/types": "src/api/types.ts", lock: "src/lock.ts" },
   format: ["esm"],
   target: "node22",
   dts: true,