新增管理員頁面、Word PDF 預覽、租賃日期欄位、SSL docker-compose

- 新增 /admin.html：上傳/刪除範本，HTTP Basic Auth 保護
- Word 預覽改用 LibreOffice PDF 轉換，帶入表單參數即時顯示
- 新增租賃開始/結束年月日、租期年數佔位符支援
- 預覽 loading 遮罩，修正 hidden 被 CSS display:flex 覆蓋的問題
- 左右欄 UI 重構，右欄固定顯示 Word 預覽
- 新增 docker-compose.yml + nginx SSL reverse proxy
- admin 密碼改由 ADMIN_PASSWORD 環境變數設定

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

docker-compose.yml

@@ -0,0 +1,35 @@
+services:
+  rental-contract-pdf:
+    container_name: rental-contract-pdf
+    image: rental-contract-pdf
+    build: .
+    restart: always
+    expose:
+      - "3001"
+    environment:
+      ADMIN_PASSWORD: "123456"
+    volumes:
+      - ./templates:/app/templates
+
+  rental-contract-pdf-web:
+    container_name: rental-contract-pdf-web
+    build:
+      context: .
+      dockerfile: docker/nginx/Dockerfile
+    image: rental-contract-pdf-web:latest
+    restart: always
+    depends_on:
+      - rental-contract-pdf
+    ports:
+      - "3001:3001"
+    environment:
+      NGINX_PORT: 3001
+      NGINX_SERVER_NAME: ${NGINX_SERVER_NAME:-_}
+      SSL_CERT_DIR: /etc/nginx/certs
+      SSL_CERT_FILE_NAME: ${SSL_CERT_FILE_NAME:-RSA-cert.pem}
+      SSL_CHAIN_FILE_NAME: ${SSL_CHAIN_FILE_NAME:-RSA-chain.pem}
+      SSL_KEY_FILE_NAME: ${SSL_KEY_FILE_NAME:-RSA-privkey.pem}
+      UPSTREAM_HOST: rental-contract-pdf
+      UPSTREAM_PORT: 3001
+    volumes:
+      - /volume1/homes/JianMiau/www/certificate:/etc/nginx/certs:ro