feat: add API Key authentication, Dockerfile, and docker-compose

- core/auth.py: API Key auth via header X-API-Key (env PDFTOOLKIT_API_KEY)
  - Modo dev: sem chave configurada → acesso livre
  - Modo produção: exige chave, retorna 401/403
- api.py: endpoints protegidos com Depends(_auth_required)
  - /health e / permanecem públicos
- Dockerfile: multi-stage (base → api → web)
- docker-compose.yml: api + web com healthcheck, volumes e rede
- .env.example: template de variáveis de ambiente
- README.md: seções de autenticação e Docker

docker-compose.yml

@@ -0,0 +1,58 @@
+services:
+
+  # ── API REST (FastAPI) ──────────────────────────────────────────
+  api:
+    build:
+      context: .
+      target: api
+    container_name: pdf-toolkit-api
+    restart: unless-stopped
+    ports:
+      - "${API_PORT:-8555}:8555"
+    env_file:
+      - .env
+    environment:
+      - PDFTOOLKIT_API_KEY=${PDFTOOLKIT_API_KEY:-}
+    volumes:
+      - uploads:/tmp/uploads
+    healthcheck:
+      test: ["CMD", "python", "-c", "import http.client; conn=http.client.HTTPConnection('localhost:8555'); conn.request('GET','/health'); r=conn.getresponse(); exit(0 if r.status==200 else 1)"]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 10s
+    networks:
+      - pdf-net
+
+  # ── Interface Web (Streamlit) ───────────────────────────────────
+  web:
+    build:
+      context: .
+      target: web
+    container_name: pdf-toolkit-web
+    restart: unless-stopped
+    ports:
+      - "${WEB_PORT:-8550}:8550"
+    depends_on:
+      - api
+    env_file:
+      - .env
+    environment:
+      - API_BASE_URL=http://api:8555
+    volumes:
+      - uploads:/tmp/uploads
+    healthcheck:
+      test: ["CMD", "python", "-c", "import http.client; conn=http.client.HTTPConnection('localhost:8550'); conn.request('GET','/'); r=conn.getresponse(); exit(0 if r.status==200 else 1)"]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 10s
+    networks:
+      - pdf-net
+
+volumes:
+  uploads:
+
+networks:
+  pdf-net:
+    driver: bridge