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.

prisma/schema.prisma

@@ -0,0 +1,33 @@
+generator client {
+  provider = "prisma-client"
+  output   = "./generated/prisma"
+}
+
+datasource db {
+  provider = "postgresql"
+  url      = env("DATABASE_URL")
+}
+
+model Trip {
+  id            String    @id @default(uuid())
+  userId        String
+  title         String
+  vehicleModel  String
+  rangeMi       Int
+  itinerary     Json
+  status        String    @default("planning")
+  isPublic      Boolean   @default(false)
+  shareSlug     String?   @unique
+  createdAt     DateTime  @default(now())
+  updatedAt     DateTime  @updatedAt
+  @@index([userId])
+}
+
+model ChatMessage {
+  id        String   @id @default(uuid())
+  tripId    String
+  role      String
+  content   String   @db.Text
+  createdAt DateTime @default(now())
+  @@index([tripId])
+}