Replace API route handlers with server actions across the app

- Delete 10 API routes (stats, system-health, update-check, jobs/trigger,
  backup/restore, person, titles import/resolve, registration/status) and
  move logic into server actions in lib/actions/settings.ts and
  lib/actions/watchlist.ts
- Refactor SystemHealthCards to accept initialData prop and hydrate Jotai
  atoms via useHydrateAtoms; replace useSystemHealth SWR hook with a
  lightweight useSystemHealthRefresh that calls getSystemHealthAction
- Convert BackupRestoreSection to use restoreBackupAction + useTransition
  instead of a raw fetch call
- Split SystemStatusCard, BackgroundJobsCard, and StorageCard into
  standalone components reading from systemHealthDataAtom
- Make SetupPage async with connection() to opt into dynamic rendering

components/update-toast.tsx

@@ -3,6 +3,7 @@
 import { useAtom } from "jotai";
 import { useEffect } from "react";
 import { toast } from "sonner";
+import { getUpdateCheckAction } from "@/lib/actions/settings";
 import { updateToastShownAtom } from "@/lib/atoms/update-check";
 
 export function UpdateToast() {
@@ -11,38 +12,21 @@ export function UpdateToast() {
   useEffect(() => {
     if (shown) return;
 
-    async function check() {
-      try {
-        const res = await fetch("/api/admin/update-check");
-        if (!res.ok) return;
+    getUpdateCheckAction().then((data) => {
+      if (!data?.updateAvailable) return;
 
-        const data = (await res.json()) as {
-          updateAvailable: boolean;
-          currentVersion: string;
-          latestVersion: string | null;
-          releaseUrl: string | null;
-        };
-
-        if (data.updateAvailable) {
-          setShown(true);
-          toast.info(`Sofa v${data.latestVersion} is available`, {
-            description: `You're running v${data.currentVersion}.`,
-            duration: 15_000,
-            action: data.releaseUrl
-              ? {
-                  label: "View release",
-                  onClick: () =>
-                    window.open(data.releaseUrl as string, "_blank"),
-                }
-              : undefined,
-          });
-        }
-      } catch {
-        // Silently ignore network errors
-      }
-    }
-
-    check();
+      setShown(true);
+      toast.info(`Sofa v${data.latestVersion} is available`, {
+        description: `You're running v${data.currentVersion}.`,
+        duration: 15_000,
+        action: data.releaseUrl
+          ? {
+              label: "View release",
+              onClick: () => window.open(data.releaseUrl as string, "_blank"),
+            }
+          : undefined,
+      });
+    });
   }, [shown, setShown]);
 
   return null;