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.

tests/grok-api-diagnostic.spec.ts

@@ -0,0 +1,44 @@
+import { test, expect } from '@playwright/test';
+
+test.describe('Grok API Diagnostic (Backend Only)', () => {
+
+  test('backend should successfully call xAI Grok and return a response', async ({ request }) => {
+    test.setTimeout(120000); // Grok can be slow
+
+    const payload = {
+      message: "Plan a short day trip from Milton Keynes to Telford in a Model Y. Include one Supercharger stop.",
+      vehicle: { name: "Model Y Long Range", rangeKm: 514 },
+      itinerary: null,
+      history: []
+    };
+
+    const response = await request.post('http://localhost:3000/api/chat', {
+      data: payload,
+      headers: { 'Content-Type': 'application/json' }
+    });
+
+    expect(response.ok()).toBeTruthy();
+
+    const body = await response.json();
+
+    console.log('[Diagnostic] Grok reply length:', body.reply?.length);
+    console.log('[Diagnostic] Has itinerary update:', !!body.itinerary);
+
+    expect(body.reply).toBeDefined();
+    expect(body.reply.length).toBeGreaterThan(50);
+
+    // It should NOT be the generic error message
+    expect(body.reply).not.toContain('having trouble reaching Grok');
+
+    // If it produced an itinerary, validate basic shape
+    if (body.itinerary) {
+      expect(body.itinerary.days).toBeDefined();
+      expect(Array.isArray(body.itinerary.days)).toBe(true);
+      expect(body.itinerary.days.length).toBeGreaterThan(0);
+      console.log('[Diagnostic] Itinerary days:', body.itinerary.days.length);
+    }
+
+    console.log('✅ Backend successfully called real Grok!');
+  });
+
+});