Fix Docker build and production server infrastructure

- Add SKIP_ENV_VALIDATION to bypass Zod env check during next build
- Bundle custom server.ts with esbuild so production uses Socket.io
- Create worker entry point (src/worker.ts) with all BullMQ workers
- Add esbuild build scripts for server and worker bundles
- Fix Dockerfile.worker to include its own build stage
- Fix pre-commit hook to work without global pnpm
- Add CLAUDE.md with project conventions and quick reference

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.husky/pre-commit

@@ -1,4 +1,4 @@
-pnpm exec lint-staged
+npx pnpm exec lint-staged
 # Verify no .env files staged
 if git diff --cached --name-only | grep -qE '\.env($|\.)'; then
   echo "❌ .env files must not be committed"