build: remove main.js from git tracking

main.js is now a build artifact produced by esbuild, not tracked in
git. The release workflow (next commit) will build and attach it to
GitHub Releases. Also removes the check-build-artifacts script that
enforced main.js stay in sync.

Change-Id: I35f7dede09c5ac3c2d788c11248e2ed4931a95bc

.gitignore

@@ -14,7 +14,8 @@ node_modules/
 dist/
 *.log
 
-# Build artifacts (source maps)
+# Build artifacts
+main.js
 main.js.map
 
 # Agent state

package.json

@@ -5,7 +5,6 @@
   "main": "main.js",
   "scripts": {
     "build": "node esbuild.config.mjs production",
-    "check:build-artifacts": "node scripts/check-build-artifacts.mjs",
     "dev": "node esbuild.config.mjs watch",
     "typecheck": "tsc --noEmit",
     "lint": "biome check main.ts src/",

scripts/check-build-artifacts.mjs

@@ -1,19 +0,0 @@
-import { execFileSync } from 'node:child_process';
-
-function diffMainJs() {
-  return execFileSync('git', ['diff', '--', 'main.js'], { encoding: 'utf8' });
-}
-
-const before = diffMainJs();
-
-execFileSync('npm', ['run', 'build'], { stdio: 'inherit' });
-
-const after = diffMainJs();
-
-if (after !== before) {
-  console.error('\nmain.js is not in sync with the TypeScript source.');
-  console.error('Run `npm run build` and include the updated main.js in the same change.');
-  process.exit(1);
-}
-
-console.log('main.js is in sync with the TypeScript source.');