chore: initial checkpoint - Tesla Roadtrip planner

- Proactive Grok integration (xAI API + local CLI fallback)
- Real road routing via OSRM (no more bird's-eye lines)
- Heavy structured logging for fast iteration
- Strong sanitization + geocoding + ErrorBoundary (no black screens)
- Playwright E2E tests (API diagnostic + full UI flow)
- scripts/dev.sh for one-command startup
- Clean .env.example + documentation

This is a stable checkpoint before further prompt/UI refinement.

server/config/env.ts

@@ -0,0 +1,17 @@
+import 'dotenv/config';
+
+export const env = {
+  port: parseInt(process.env.PORT || '3000', 10),
+  nodeEnv: process.env.NODE_ENV || 'development',
+  appUrl: process.env.APP_URL || 'https://tesla-roadtrip.test',
+  apiUrl: process.env.API_URL || 'https://tesla-roadtrip.test',
+
+  // Auth
+  authSecret: process.env.AUTH_SECRET || '',
+  authUrl: process.env.AUTH_URL || 'https://auth.tony.codes',
+
+  // Grok / xAI
+  grokBin: process.env.GROK_BIN || '/usr/local/bin/grok',
+  xaiApiKey: process.env.XAI_API_KEY || '',
+  grokEnabled: process.env.GROK_ENABLED !== 'false',
+} as const;