feat(server): 系统缓存清理接口与 OCR 文本层兜底增强

- 新增 system_cache 模块与 POST /settings/cache/clear，管理员可一键清理 OCR 结果/运行时配置/模型失败冷却/知识库索引/地点语义等进程内缓存
- 各服务暴露 clear_*_cache 方法（ocr/runtime_settings/runtime_chat/knowledge/application_location_semantic），SettingsCacheClearRead 汇总清理项
- OCR 转图片失败时尝试用 PDF 文本层兜底构建识别文档（有效字符≥8），并写结果缓存；OcrService 暴露 clear_result_cache
- receipt_folder 车票过滤补充身份证号关键词，附件文档/操作/展示模块同步适配
- 新增 system_cache_endpoints 测试，更新 openapi_schema/ocr/receipt_folder/attachment_association_jobs 测试

server/tests/test_system_cache_endpoints.py

@@ -0,0 +1,91 @@
+from __future__ import annotations
+
+from collections.abc import Generator
+
+from fastapi.testclient import TestClient
+from sqlalchemy import create_engine
+from sqlalchemy.orm import Session, sessionmaker
+from sqlalchemy.pool import StaticPool
+
+from app.api.deps import get_db
+from app.db.base import Base
+from app.main import create_app
+from app.schemas.ocr import OcrRecognizeDocumentRead
+from app.services.ocr import OcrService
+
+
+def build_client() -> TestClient:
+    engine = create_engine(
+        "sqlite+pysqlite:///:memory:",
+        connect_args={"check_same_thread": False},
+        poolclass=StaticPool,
+    )
+    Base.metadata.create_all(bind=engine)
+    session_factory = sessionmaker(bind=engine, autoflush=False, autocommit=False)
+    app = create_app()
+
+    def override_db() -> Generator[Session, None, None]:
+        db = session_factory()
+        try:
+            yield db
+        finally:
+            db.close()
+
+    app.dependency_overrides[get_db] = override_db
+    return TestClient(app)
+
+
+def _seed_ocr_cache() -> None:
+    OcrService._write_cached_document(
+        "pytest-cache-key",
+        OcrRecognizeDocumentRead(
+            filename="receipt.pdf",
+            media_type="application/pdf",
+            text="旧 OCR 缓存",
+            summary="旧 OCR 缓存",
+        ),
+    )
+
+
+def test_clear_settings_cache_endpoint_clears_ocr_result_cache() -> None:
+    OcrService.clear_result_cache()
+    _seed_ocr_cache()
+    assert len(OcrService._result_cache) == 1
+
+    client = build_client()
+    response = client.post(
+        "/api/v1/settings/cache/clear",
+        headers={
+            "x-auth-username": "admin",
+            "x-auth-name": "Admin",
+            "x-auth-is-admin": "true",
+        },
+    )
+
+    assert response.status_code == 200
+    payload = response.json()
+    assert payload["totalCleared"] >= 1
+    assert {
+        "cacheKey": "ocr_result_cache",
+        "label": "OCR 识别结果缓存",
+        "clearedCount": 1,
+    } in payload["items"]
+    assert len(OcrService._result_cache) == 0
+
+
+def test_clear_settings_cache_endpoint_requires_admin() -> None:
+    OcrService.clear_result_cache()
+    _seed_ocr_cache()
+
+    client = build_client()
+    response = client.post(
+        "/api/v1/settings/cache/clear",
+        headers={
+            "x-auth-username": "ordinary-user",
+            "x-auth-name": "Ordinary User",
+        },
+    )
+
+    assert response.status_code == 403
+    assert len(OcrService._result_cache) == 1
+    OcrService.clear_result_cache()