feat: 查询页增强 + 权限体系优化

- Redis DB0~DB15 下拉选择，默认DB0
- 查询历史粘贴按钮（一键填入SQL编辑器）
- 去掉导出历史按钮
- SchemaSidebar 按目标数据库筛选
- SQL自动补全 schema 双层注册（db→tables, table→columns）
- 后端 db-schema 接口（INFORMATION_SCHEMA.COLUMNS 一次加载）
- autocompletion 扩展激活
- Redis key 树形结构（冒号分隔层级）
- Redis 查询模板 GET/HGETALL/HGET
- guest 角色彻底移除，改为 auditor
- 登录页优化：去掉演示账号、placeholder 中文提示

backend/app/api/v1/endpoints/auth.py

@@ -22,6 +22,9 @@ async def login(req: LoginRequest, db: AsyncSession = Depends(get_db)):
     if not user.is_active:
         raise HTTPException(status_code=403, detail="用户已禁用")
 
+    if user.role == "guest":
+        raise HTTPException(status_code=403, detail="访客账户已禁用，请联系管理员")
+
     user.last_login = datetime.now(timezone.utc)
     await db.commit()
 

backend/app/api/v1/endpoints/instance_detail.py

@@ -30,7 +30,7 @@ async def _get_decrypted_instance(db: AsyncSession, instance_id: int) -> Instanc
     return instance
 
 
-async def _mysql_query(instance: Instance, sql: str, database: Optional[str] = None) -> list:
+async def _mysql_query(instance: Instance, sql: str, database: Optional[str] = None, params: Optional[list] = None) -> list:
     """Execute a MySQL query and return rows as list of dicts."""
     import aiomysql
     conn = await aiomysql.connect(
@@ -40,7 +40,7 @@ async def _mysql_query(instance: Instance, sql: str, database: Optional[str] = N
     )
     try:
         async with conn.cursor(aiomysql.DictCursor) as cur:
-            await cur.execute(sql)
+            await cur.execute(sql, params)
             rows = await cur.fetchall()
         return rows
     finally:
@@ -120,6 +120,38 @@ async def list_tables(
         raise HTTPException(status_code=500, detail="查询表列表失败: " + str(e))
 
 
+# ---- DB Schema (for autocomplete) ----
+
+@router.get("/{instance_id}/detail/db-schema")
+async def get_db_schema(
+    instance_id: int,
+    database: str = Query(..., description="数据库名"),
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(require_role("admin", "dba", "developer")),
+):
+    """一次性返回整个库的 {table: [columns]} 结构，用于前端 SQL 自动补全"""
+    instance = await _get_decrypted_instance(db, instance_id)
+    await check_instance_access(current_user, instance, db)
+    if instance.db_type != "mysql":
+        raise HTTPException(status_code=400, detail="仅支持MySQL实例")
+    try:
+        rows = await _mysql_query(
+            instance,
+            "SELECT TABLE_NAME, COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS "
+            "WHERE TABLE_SCHEMA = %s ORDER BY TABLE_NAME, ORDINAL_POSITION",
+            database=database,
+            params=[database],
+        )
+        schema: dict[str, list[str]] = {}
+        for row in rows:
+            tbl = row["TABLE_NAME"]
+            col = row["COLUMN_NAME"]
+            schema.setdefault(tbl, []).append(col)
+        return schema
+    except Exception as e:
+        raise HTTPException(status_code=500, detail="获取库结构失败: " + str(e))
+
+
 # ---- Table Detail ----
 
 @router.get("/{instance_id}/detail/table-detail")