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/services/system_service.py

@@ -0,0 +1,45 @@
+"""主机 CPU / 内存 / 磁盘信息采集（基于 psutil）。"""
+
+from __future__ import annotations
+
+import platform
+import time
+
+import psutil
+
+from ..schemas.system import DiskUsage, MemoryUsage, SystemStatus
+
+# 跳过的伪文件系统
+_IGNORED_FSTYPES = {"squashfs", "tmpfs", "devtmpfs", "overlay"}
+
+
+class SystemService:
+    def get_status(self) -> SystemStatus:
+        vm = psutil.virtual_memory()
+        memory = MemoryUsage(
+            total=vm.total, available=vm.available, used=vm.used, percent=vm.percent,
+        )
+
+        disks: list[DiskUsage] = []
+        seen: set[str] = set()
+        for part in psutil.disk_partitions(all=False):
+            if part.fstype in _IGNORED_FSTYPES or part.mountpoint in seen:
+                continue
+            try:
+                u = psutil.disk_usage(part.mountpoint)
+            except (PermissionError, OSError):
+                continue
+            seen.add(part.mountpoint)
+            disks.append(DiskUsage(
+                device=part.device, mountpoint=part.mountpoint, fstype=part.fstype,
+                total=u.total, used=u.used, free=u.free, percent=u.percent,
+            ))
+
+        return SystemStatus(
+            hostname=platform.node(),
+            cpu_percent=psutil.cpu_percent(interval=0.5),
+            cpu_count=psutil.cpu_count(logical=True) or 0,
+            memory=memory,
+            disks=disks,
+            uptime_seconds=max(0.0, time.time() - psutil.boot_time()),
+        )