feat: add docker deployment stack

Add container definitions for the web app, API, worker, and PostGIS database so the local stack can be built and run consistently.

docker-compose.yml

@@ -0,0 +1,57 @@
+services:
+  db:
+    image: postgis/postgis:16-3.4
+    environment:
+      POSTGRES_DB: leads4less
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: change-me
+    volumes:
+      - leads4less-db:/var/lib/postgresql/data
+
+  api:
+    build:
+      context: .
+      target: api
+    depends_on:
+      - db
+    environment:
+      NODE_ENV: production
+      APP_HOST: 0.0.0.0
+      APP_PORT: 4000
+      APP_ORIGIN: https://app.example.com
+      DATABASE_URL: postgres://postgres:change-me@db:5432/leads4less
+      COOKIE_SECRET: replace-with-long-random-secret
+      GOOGLE_MAPS_SERVER_KEY: your-server-key
+      PG_BOSS_SCHEMA: pgboss
+      SESSION_TTL_DAYS: 30
+    expose:
+      - "4000"
+
+  worker:
+    build:
+      context: .
+      target: worker
+    depends_on:
+      - db
+    environment:
+      NODE_ENV: production
+      DATABASE_URL: postgres://postgres:change-me@db:5432/leads4less
+      COOKIE_SECRET: replace-with-long-random-secret
+      GOOGLE_MAPS_SERVER_KEY: your-server-key
+      PG_BOSS_SCHEMA: pgboss
+      SESSION_TTL_DAYS: 30
+
+  web:
+    build:
+      context: .
+      target: web
+      args:
+        VITE_API_BASE_URL: https://api.example.com/api
+        VITE_GOOGLE_MAPS_PLATFORM_KEY: your-browser-key
+    depends_on:
+      - api
+    expose:
+      - "80"
+
+volumes:
+  leads4less-db: