feat(server): 新增系统日志服务模块，包含API端点、schema定义和服务实现，用于系统操作日志记录和查询

server/tests/test_system_logs_service.py

@@ -0,0 +1,54 @@
+from __future__ import annotations
+
+from app.services.system_logs import SystemLogService
+
+
+def test_system_log_service_reads_tail(tmp_path) -> None:
+    log_dir = tmp_path / "logs"
+    log_dir.mkdir(parents=True, exist_ok=True)
+    log_file = log_dir / "app.log"
+    log_file.write_text(
+        "\n".join(f"line-{index}" for index in range(1, 21)) + "\n",
+        encoding="utf-8",
+    )
+
+    service = SystemLogService(log_dir=log_dir)
+    files = service.list_files()
+    tail = service.read_tail("app.log", line_limit=5)
+
+    assert [item.name for item in files] == ["app.log"]
+    assert tail.name == "app.log"
+    assert tail.line_count == 5
+    assert tail.lines == ["line-16", "line-17", "line-18", "line-19", "line-20"]
+
+
+def test_system_log_service_parses_entries(tmp_path) -> None:
+    log_dir = tmp_path / "logs"
+    log_dir.mkdir(parents=True, exist_ok=True)
+    log_file = log_dir / "app.log"
+    log_file.write_text(
+        "\n".join(
+            [
+                "2026-05-15 09:00:00 | INFO     | app.middleware.access | GET /api/v1/health 200 8.2ms request_id=req_1",
+                "2026-05-15 09:00:01 | WARNING  | app.services.settings | Skipping undecryptable model API key",
+                "2026-05-15 09:00:02 | ERROR    | app.services.demo | Failed to load plugin",
+                "Traceback line 1",
+            ]
+        )
+        + "\n",
+        encoding="utf-8",
+    )
+
+    service = SystemLogService(log_dir=log_dir)
+    entries = service.list_entries(entry_limit=10)
+
+    assert len(entries) == 3
+    assert entries[0].level == "ERROR"
+    assert entries[0].event_type == "系统异常"
+    assert "Traceback line 1" in entries[0].raw
+    assert entries[1].outcome == "告警"
+    assert entries[2].event_type == "HTTP 请求"
+    assert entries[2].method == "GET"
+    assert entries[2].status_code == 200
+    assert entries[2].request_id == "req_1"
+    assert service.get_entry(entries[2].id).id == entries[2].id