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/routes/chat.ts

@@ -0,0 +1,73 @@
+import { Router } from 'express';
+import { z } from 'zod';
+import { grok } from '../services/llm/GrokHeadlessClient.js';
+import { createLogger } from '../lib/logger.js';
+import crypto from 'crypto';
+
+const log = createLogger('chat-api');
+const router = Router();
+
+const ChatRequestSchema = z.object({
+  message: z.string().min(1).max(2000),
+  vehicle: z.object({ name: z.string(), rangeKm: z.number() }),
+  itinerary: z.any().optional(),
+  history: z.array(z.object({ role: z.enum(['user', 'assistant']), content: z.string() })).optional(),
+});
+
+router.post('/chat', async (req, res) => {
+  const requestId = crypto.randomUUID().slice(0, 8);
+  const start = Date.now();
+
+  log.info({ requestId, body: req.body }, '=== INCOMING /api/chat REQUEST ===');
+
+  try {
+    const parsed = ChatRequestSchema.safeParse(req.body);
+    if (!parsed.success) {
+      log.error({ requestId, errors: parsed.error.format() }, 'Invalid request body');
+      return res.status(400).json({ error: 'Invalid request' });
+    }
+
+    const { message, vehicle, itinerary, history = [] } = parsed.data;
+
+    log.info({
+      requestId,
+      userMessage: message,
+      vehicle: vehicle.name,
+      historyLength: history.length,
+      currentItineraryDays: itinerary?.days?.length || 0,
+    }, 'Parsed chat request');
+
+    // Call Grok (this will produce very detailed logs inside GrokHeadlessClient)
+    const result = await grok.chat(
+      [...history, { role: 'user' as const, content: message }],
+      itinerary,
+      vehicle
+    );
+
+    const duration = Date.now() - start;
+
+    const payload: any = { reply: result.text };
+    if (result.updatedItinerary) {
+      payload.itinerary = result.updatedItinerary;
+    }
+
+    log.info({
+      requestId,
+      durationMs: duration,
+      replyLength: result.text.length,
+      itineraryUpdated: !!result.updatedItinerary,
+      newDays: result.updatedItinerary?.days?.length || 0,
+    }, '=== SENDING RESPONSE TO FRONTEND ===');
+
+    if (result.updatedItinerary) {
+      log.debug({ requestId, fullItinerary: result.updatedItinerary }, 'Full updated itinerary being sent');
+    }
+
+    res.json(payload);
+  } catch (err) {
+    log.error({ requestId, err }, 'Chat route crashed');
+    res.status(500).json({ reply: "Something went wrong on the server." });
+  }
+});
+
+export default router;