init: 从 /root/zikai 根目录迁入

把原本散落在 /root/zikai 的 FastAPI 服务整理到 server/ 子目录，
开启独立 git 与 venv。运行时数据（config.yaml / keys / uploads）
按 .gitignore 留在工作目录但不入仓。

app/controllers/system_controller.py

@@ -0,0 +1,39 @@
+"""系统监控接口。"""
+
+from __future__ import annotations
+
+from fastapi import APIRouter, Request
+from fastapi.responses import HTMLResponse, JSONResponse, Response
+
+from ..schemas.system import SystemStatus
+from ..services.system_service import SystemService
+from ..views.system_status_html import render as render_status_html
+
+router = APIRouter(prefix="/api/system", tags=["system"])
+
+
+def _wants_html(request: Request, fmt: str | None) -> bool:
+    if fmt == "json":
+        return False
+    if fmt == "html":
+        return True
+    accept = request.headers.get("accept", "").lower()
+    return "text/html" in accept and "application/json" not in accept
+
+
+@router.get(
+    "/status",
+    summary="主机资源状态（HTML 或 JSON）",
+    description=(
+        "返回 CPU、内存、磁盘的实时使用情况（数据来源 psutil）。\n\n"
+        "**内容协商**：浏览器（`Accept: text/html`）返回 HTML 页面，API 客户端返回 JSON。"
+        "可用 `?format=html` / `?format=json` 强制指定。"
+    ),
+    response_model=SystemStatus,
+    responses={200: {"content": {"application/json": {}, "text/html": {"schema": {"type": "string"}}}}},
+)
+def get_status(request: Request, format: str | None = None) -> Response:
+    status = SystemService().get_status()
+    if _wants_html(request, format):
+        return HTMLResponse(render_status_html(status))
+    return JSONResponse(status.model_dump(mode="json"))