Add Redis caching, email refresh button, optimize page loading

- Add Redis service (docker-compose) for caching accounts, messages, payment status
- Cache accounts list (5min), messages (3min), payment status (10min)
- Auto-invalidate cache on import/delete/payment-check/note-update
- Add refresh button to email list panel (force re-fetch from IMAP)
- Messages API supports refresh=true param to bypass cache
- New cache.py module with RedisCache class

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

docker-compose.yml

@@ -16,8 +16,12 @@ services:
     environment:
       # 管理员令牌，可以通过环境变量设置
       - ADMIN_TOKEN=${ADMIN_TOKEN:-admin123}
+      - REDIS_URL=redis://redis:6379/0
       # 可选：设置时区
       - TZ=Asia/Shanghai
+    depends_on:
+      redis:
+        condition: service_healthy
     restart: unless-stopped
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:5001/"]
@@ -28,6 +32,24 @@ services:
     networks:
       - outlook-mail-network
 
+  redis:
+    image: redis:7-alpine
+    container_name: outlook-redis
+    command: redis-server --maxmemory 64mb --maxmemory-policy allkeys-lru
+    volumes:
+      - redis_data:/data
+    restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "redis-cli", "ping"]
+      interval: 10s
+      timeout: 3s
+      retries: 3
+    networks:
+      - outlook-mail-network
+
+volumes:
+  redis_data:
+
 networks:
   outlook-mail-network:
-    driver: bridge
+    driver: bridge