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/src/app/schemas/system_log.py

@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+from datetime import datetime
+
+from pydantic import BaseModel, Field
+
+
+class SystemLogFileRead(BaseModel):
+    name: str
+    size_bytes: int = 0
+    updated_at: datetime | None = None
+
+
+class SystemLogTailRead(BaseModel):
+    name: str
+    size_bytes: int = 0
+    updated_at: datetime | None = None
+    line_count: int = 0
+    lines: list[str] = Field(default_factory=list)
+
+
+class SystemLogEntryRead(BaseModel):
+    id: str
+    source_file: str
+    line_number: int = 0
+    timestamp: datetime | None = None
+    level: str = "UNKNOWN"
+    logger: str = ""
+    message: str = ""
+    request_id: str = ""
+    method: str = ""
+    path: str = ""
+    status_code: int | None = None
+    duration_ms: float | None = None
+    event_type: str = "系统日志"
+    outcome: str = "未知"
+    summary: str = ""
+    parse_status: str = "parsed"
+    raw: str = ""