feat: add docker-compose.dev.yml for local development

- docker-compose.dev.yml: backend on 8000, frontend (Vite) on 5173
- Backend mounts source files + uvicorn --reload for hot reload
- Frontend uses node:20-alpine, mounts ./frontend, runs npm run dev --host
- vite.config.ts: proxy target reads from API_TARGET env var
  (defaults to localhost:8000 for plain npm run dev,
   set to http://backend:8000 by docker-compose.dev.yml)

Usage: docker compose -f docker-compose.dev.yml up

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

flight-comparator/docker-compose.dev.yml

@@ -0,0 +1,41 @@
+services:
+  backend:
+    build:
+      context: .
+      dockerfile: Dockerfile.backend
+    container_name: flight-radar-backend-dev
+    restart: unless-stopped
+    ports:
+      - "8000:8000"
+    environment:
+      - DATABASE_PATH=/app/data/cache.db
+    volumes:
+      # Mount source files so uvicorn --reload picks up changes
+      - ./api_server.py:/app/api_server.py
+      - ./airports.py:/app/airports.py
+      - ./cache.py:/app/cache.py
+      - ./database:/app/database
+      - flight-radar-data-dev:/app/data
+    command: uvicorn api_server:app --host 0.0.0.0 --port 8000 --reload
+
+  frontend:
+    image: node:20-alpine
+    container_name: flight-radar-frontend-dev
+    working_dir: /app
+    restart: unless-stopped
+    ports:
+      - "5173:5173"
+    environment:
+      # Tells Vite's proxy where to find the backend inside Docker
+      - API_TARGET=http://backend:8000
+    volumes:
+      - ./frontend:/app
+      # Isolate node_modules inside the container (don't use host's)
+      - /app/node_modules
+    command: sh -c "npm install && npm run dev -- --host"
+    depends_on:
+      - backend
+
+volumes:
+  flight-radar-data-dev:
+    driver: local

flight-comparator/frontend/vite.config.ts

@@ -1,20 +1,18 @@
 import { defineConfig } from 'vite'
 import react from '@vitejs/plugin-react'
 
+// When running inside Docker the backend is reachable via its service name.
+// Outside Docker (plain `npm run dev`) it falls back to localhost.
+const apiTarget = process.env.API_TARGET ?? 'http://localhost:8000'
+
 // https://vite.dev/config/
 export default defineConfig({
   plugins: [react()],
   server: {
     port: 5173,
     proxy: {
-      '/api': {
-        target: 'http://localhost:8000',
-        changeOrigin: true,
-      },
-      '/health': {
-        target: 'http://localhost:8000',
-        changeOrigin: true,
-      }
+      '/api': { target: apiTarget, changeOrigin: true },
+      '/health': { target: apiTarget, changeOrigin: true },
     }
   }
 })