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.

scripts/dev.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+
+# One-command development script for Tesla Roadtrip
+# Usage: ./scripts/dev.sh
+
+set -e
+
+echo "🚀 Starting Tesla Roadtrip development environment..."
+
+# Load .env if it exists
+if [ -f .env ]; then
+  set -a
+  source .env
+  set +a
+fi
+
+# Check for XAI_API_KEY
+if [ -z "$XAI_API_KEY" ]; then
+  echo ""
+  echo "⚠️  XAI_API_KEY is not set."
+  echo "   → Real Grok (via xAI API) will NOT work."
+  echo "   → The app will fall back to very basic responses."
+  echo ""
+  echo "   To fix this:"
+  echo "   1. Add this line to your .env file:"
+  echo "      XAI_API_KEY=xai-YourKeyHere"
+  echo ""
+  echo "   2. Or export it before running:"
+  echo "      export XAI_API_KEY=xai-YourKeyHere"
+  echo ""
+  read -p "Continue without real Grok? (y/N) " -n 1 -r
+  echo
+  if [[ ! $REPLY =~ ^[Yy]$ ]]; then
+    echo "Exiting..."
+    exit 1
+  fi
+else
+  echo "✅ XAI_API_KEY found — real Grok API will be used"
+fi
+
+echo ""
+echo "Starting Backend + Frontend..."
+echo "  Backend:   http://localhost:3000"
+echo "  Frontend:  http://localhost:5173"
+echo ""
+
+# Run both with nice colored labels
+npx concurrently \
+  -n "BACKEND,FRONTEND" \
+  -c "cyan,green" \
+  --kill-others-on-fail \
+  "npm run dev:server" \
+  "npm --prefix client run dev"