Update docs and screenshots

backend/app/system/__init__.py

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+from app.system.service import SystemControlService
+
+__all__ = ["SystemControlService"]

backend/app/system/service.py

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+from __future__ import annotations
+
+import asyncio
+import os
+from dataclasses import dataclass
+
+from app.core.config import get_settings
+
+
+@dataclass(slots=True)
+class SystemCommandResult:
+    accepted: bool
+    action: str
+    status: str
+    detail: str
+
+    def as_dict(self) -> dict[str, object]:
+        return {
+            "accepted": self.accepted,
+            "action": self.action,
+            "status": self.status,
+            "detail": self.detail,
+        }
+
+
+class SystemControlService:
+    def __init__(self) -> None:
+        settings = get_settings()
+        self._enabled = settings.system_control_enabled
+        self._platform = os.name
+        self._helper = settings.system_control_helper
+
+    async def restart_service(self) -> dict[str, object]:
+        return (await self._run_helper(
+            action="restart-service",
+            helper_action="restart-service",
+        )).as_dict()
+
+    async def reboot_host(self) -> dict[str, object]:
+        return (await self._run_helper(
+            action="reboot-host",
+            helper_action="reboot-host",
+        )).as_dict()
+
+    async def _run_helper(
+        self,
+        *,
+        action: str,
+        helper_action: str,
+    ) -> SystemCommandResult:
+        if not self._enabled:
+            return SystemCommandResult(
+                accepted=False,
+                action=action,
+                status="disabled",
+                detail="Systemkontrol er deaktiveret i serverkonfigurationen.",
+            )
+        if self._platform != "posix":
+            return SystemCommandResult(
+                accepted=False,
+                action=action,
+                status="unsupported-platform",
+                detail="Systemkontrol understoettes kun paa Linux/systemd-installationer.",
+            )
+        if not os.path.exists(self._helper):
+            return SystemCommandResult(
+                accepted=False,
+                action=action,
+                status="helper-missing",
+                detail="Systemkontrol-helperen findes ikke paa maskinen.",
+            )
+
+        process = await asyncio.create_subprocess_exec(
+            "sudo",
+            "-n",
+            self._helper,
+            helper_action,
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.PIPE,
+        )
+        stdout, stderr = await process.communicate()
+        if process.returncode != 0:
+            error_output = (stderr or stdout).decode("utf-8", errors="ignore").strip() or "Ukendt fejl"
+            return SystemCommandResult(
+                accepted=False,
+                action=action,
+                status="command-failed",
+                detail=f"Kunne ikke planlaegge handlingen: {error_output}",
+            )
+
+        return SystemCommandResult(
+            accepted=True,
+            action=action,
+            status="scheduled",
+            detail="Handling planlagt. Serveren kan blive utilgaengelig et kort oeje.",
+        )