feat: T1.4 健康度仪表盘 — 后端聚合 API + 前端驾驶舱

- 后端：dashboard 路由（summary 聚合 + scores 列表）
- 前端：驾驶舱首页（KPI 卡片 + 健康度概览）
- 测试：4 个仪表盘测试（总计 37 tests passed）
- 前端构建 12 路由成功

backend/app/main.py

@@ -12,6 +12,7 @@ from fastapi.responses import JSONResponse
 
 from app.routers.auth import router as auth_router
 from app.routers.companies import router as companies_router
+from app.routers.dashboard import router as dashboard_router
 from app.routers.reports import router as reports_router
 from app.schemas.common import error
 
@@ -71,3 +72,4 @@ async def health_check():
 app.include_router(auth_router, prefix="/api/v1")
 app.include_router(companies_router, prefix="/api/v1")
 app.include_router(reports_router, prefix="/api/v1")
+app.include_router(dashboard_router, prefix="/api/v1")