智教助手平台：完整初始化

- 前端：Vue3 + TS + Element Plus，24 个页面路由（课件/组题/教案/动画/思维导图/作文批改/命题/课堂/资源/社区等）
- 后端：FastAPI + SQLAlchemy + SQLite，17 个路由模块，AI 服务层含降级模板
- AI：glm-5.x 推理模型已禁用思维链，确保输出真实内容
- 修复：ai_service 两处请求体注入 enable_thinking/thinking disabled
- 测试账号：13900999999 / test1234

backend/database.py

@@ -0,0 +1,40 @@
+from sqlalchemy import create_engine, event
+from sqlalchemy.orm import sessionmaker, DeclarativeBase
+from config import get_settings
+
+settings = get_settings()
+
+_is_sqlite = "sqlite" in settings.DATABASE_URL
+
+engine = create_engine(
+    settings.DATABASE_URL,
+    connect_args={"check_same_thread": False} if _is_sqlite else {},
+    echo=settings.DEBUG,
+)
+
+# SQLite concurrency hardening: enable WAL mode + busy_timeout on every connection.
+# WAL allows concurrent readers alongside a single writer, eliminating most
+# "database is locked" errors under FastAPI's threaded request handling.
+if _is_sqlite:
+    @event.listens_for(engine, "connect")
+    def _set_sqlite_pragma(dbapi_conn, conn_record):
+        cur = dbapi_conn.cursor()
+        cur.execute("PRAGMA journal_mode=WAL")
+        cur.execute("PRAGMA synchronous=NORMAL")
+        cur.execute("PRAGMA busy_timeout=10000")
+        cur.execute("PRAGMA foreign_keys=ON")
+        cur.close()
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()