fix(build): output server bundle as .cjs for ES module compatibility

- Change server output from index.js to index.cjs
- Update start script to run index.cjs
- Fixes 'module is not defined' error on Railway
- CommonJS format explicit with .cjs extension

Resolves module format conflict where package.json has 'type: module'
but server bundle uses CommonJS format

package.json

@@ -18,7 +18,7 @@
     "cap:live-reload:ios": "tsx script/capacitor-live-reload.ts --ios",
     "cap:production": "tsx script/capacitor-production.ts",
     "dev:mobile": "npm run cap:live-reload && concurrently \"npm run dev\" \"echo 'Dev server started. Open Android Studio or Xcode to run the app.'\"",
-    "start": "cross-env NODE_ENV=production node dist/index.js",
+    "start": "cross-env NODE_ENV=production node dist/index.cjs",
     "check": "tsc",
     "db:push": "drizzle-kit push",
     "tauri": "cd shell/aethex-shell && npm run tauri",

script/build.ts

@@ -61,7 +61,7 @@ async function buildAll() {
     platform: "node",
     bundle: true,
     format: "cjs",
-    outfile: "dist/index.js",
+    outfile: "dist/index.cjs",
     define: {
       "process.env.NODE_ENV": '"production"',
     },