feat: v2 Vue3 frontend + multiple optimizations

- New Vue 3 + Vite frontend at /v2/ (OLED dark theme, Fira Sans/Code)
- Date selector: support day/week/month range (backend unchanged)
- SSE auto-reconnect (up to 3 retries)
- Visibility polling pause (dashboard pauses when tab hidden)
- Friendly Chinese HTTP error messages
- Cancel task with confirmation in Dashboard
- Split AiWorkflowService (1700->845 lines):
  - AiApiService: AI API calls + streaming
  - ExcelExportService: POI Excel generation
- Dockerfile: 3-stage build (Node frontend -> Maven -> JRE)
- WebApplication.java: System.out -> Logger
- .gitignore: v2 build output, backup dirs

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker-compose.yml

@@ -3,9 +3,12 @@ services:
     build:
       context: .
       dockerfile: Dockerfile
+      args:
+        # Docker 镜像加速（默认 Docker Hub，国内可设阿里云）
+        # 使用方式: REGISTRY_MIRROR=registry.cn-hangzhou.aliyuncs.com/library docker compose build
+        REGISTRY_MIRROR: ${REGISTRY_MIRROR:-docker.1ms.run/library}
     container_name: svn-log-tool
-    ports:
-      - "18088:18088"
+    network_mode: host
     volumes:
       - ./outputs:/app/outputs
     restart: unless-stopped