Add brain memory services and APIs

Introduce the backend pieces for brain memory ingestion, routing, and
system telemetry so the new knowledge workflows can project data into a
brain view. The supporting tests lock in the new behavior and keep the
expanded backend surface stable.

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

backend/app/main.py

@@ -1,6 +1,8 @@
 from contextlib import asynccontextmanager
 from fastapi import FastAPI
+from fastapi.exceptions import RequestValidationError
 from fastapi.middleware.cors import CORSMiddleware
+from starlette.exceptions import HTTPException as StarletteHTTPException
 from app.database import init_db
 import app.models  # noqa: F401 - 注册所有模型
 from app.routers import (
@@ -16,20 +18,37 @@ from app.routers import (
     folder_router,
     skill_router,
     log_router,
+    system_router,
+    brain_router,
 )
 from app.routers.scheduler import router as scheduler_router
 from app.services.scheduler_service import start_scheduler, stop_scheduler, get_scheduler_status
 from app.config import settings
+from app.logging_utils import (
+    setup_logging,
+    request_logging_middleware,
+    log_http_exception,
+    log_validation_exception,
+    log_unhandled_exception,
+    persist_system_log,
+)
 import os
 
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     # 启动
+    setup_logging(settings.DEBUG)
     os.makedirs(settings.DATA_DIR, exist_ok=True)
     os.makedirs(settings.UPLOAD_DIR, exist_ok=True)
     os.makedirs(settings.CHROMA_PERSIST_DIR, exist_ok=True)
     await init_db()
+    await persist_system_log(
+        message="application_started",
+        source="app",
+        operation="app.startup",
+        details={"version": settings.APP_VERSION},
+    )
     start_scheduler()
     yield
     # 关闭
@@ -50,6 +69,10 @@ app.add_middleware(
     allow_methods=["*"],
     allow_headers=["*"],
 )
+app.middleware("http")(request_logging_middleware)
+app.add_exception_handler(StarletteHTTPException, log_http_exception)
+app.add_exception_handler(RequestValidationError, log_validation_exception)
+app.add_exception_handler(Exception, log_unhandled_exception)
 
 # 注册路由
 app.include_router(auth_router)
@@ -64,6 +87,8 @@ app.include_router(settings_router)
 app.include_router(folder_router)
 app.include_router(skill_router)
 app.include_router(log_router)
+app.include_router(system_router)
+app.include_router(brain_router)
 app.include_router(scheduler_router)