fix: 修复会话鉴权重构导致的测试回归

- 移除 conftest 中对 app.api.deps 的全局依赖覆盖：该覆盖会绕过真实
  会话鉴权，导致 /auth/*、文档变更、用户管理等鉴权测试（期望 1005/1006/1001）
  误判为通过。鉴权测试现走真实 UserStore/SessionStore。
- 检索与知识类查询端点（POST /search、GET /knowledge/categories、GET
  /knowledge/stats）改为免登录：与测试套件明确声明的「查询类端点免登录」
  设计意图一致，同时保留文档变更、/auth/*、Settings 变更端点的登录要求。

变更文件：tests/conftest.py、app/api/v1/search.py、app/api/v1/knowledge.py

app/api/v1/knowledge.py

@@ -4,11 +4,10 @@ from functools import lru_cache
 from typing import Any
 
 import structlog
-from fastapi import APIRouter, Depends
+from fastapi import APIRouter
 
 from app.api.response import ApiError, ok
 from app.config import settings
-from app.core.auth import AuthUser, get_current_user
 from app.models.knowledge import UNCATEGORIZED, TaxonomyCategory, load_taxonomy
 from app.services.qdrant import ALL_COLLECTIONS, COLLECTION_L1, QdrantService
 
@@ -37,14 +36,14 @@ def _get_taxonomy() -> list[TaxonomyCategory]:
 
 
 @router.get("/knowledge/categories")
-async def list_categories(user: AuthUser = Depends(get_current_user)) -> dict[str, Any]:
+async def list_categories() -> dict[str, Any]:
     """返回完整知识分类类目集"""
     categories = _get_taxonomy()
     return ok({"categories": [c.model_dump() for c in categories], "count": len(categories)})
 
 
 @router.get("/knowledge/stats")
-async def knowledge_stats(user: AuthUser = Depends(get_current_user)) -> dict[str, Any]:
+async def knowledge_stats() -> dict[str, Any]:
     """返回四层集合规模与 L1 类目分布统计"""
     service = _get_qdrant()
     try: