feat: initial FitCoach Pro lead management app

Next.js 16 app with full CRUD lead management:
- REST API (/api/leads) with GET (pagination), POST, PUT, DELETE (soft delete)
- Zod validation (server + client), Supabase (PostgreSQL)
- Responsive UI: leads table (desktop) + cards (mobile), modal form, toast notifications
- 43 tests (Vitest + React Testing Library): validation, components, pagination
- Docker setup (multi-stage build, health check)
- Supabase migration + 15 seed leads
- Documentation (CLAUDE.md, README, API docs)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,22 @@
+services:
+  app:
+    build:
+      context: .
+      dockerfile: Dockerfile
+      args:
+        NEXT_PUBLIC_SUPABASE_URL: ${NEXT_PUBLIC_SUPABASE_URL}
+        NEXT_PUBLIC_SUPABASE_ANON_KEY: ${NEXT_PUBLIC_SUPABASE_ANON_KEY}
+    ports:
+      - "3000:3000"
+    environment:
+      - NODE_ENV=production
+      - NEXT_PUBLIC_SUPABASE_URL=${NEXT_PUBLIC_SUPABASE_URL}
+      - NEXT_PUBLIC_SUPABASE_ANON_KEY=${NEXT_PUBLIC_SUPABASE_ANON_KEY}
+      - SUPABASE_SERVICE_ROLE_KEY=${SUPABASE_SERVICE_ROLE_KEY}
+    restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "wget", "--no-verbose", "--tries=1", "--spider", "http://localhost:3000/"]
+      interval: 30s
+      timeout: 3s
+      start_period: 10s
+      retries: 3