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

lib/actions/watchlist.ts

@@ -1,9 +1,16 @@
 "use server";
 
 import { and, eq } from "drizzle-orm";
+import { z } from "zod";
 import { getSession, requireSession } from "@/lib/auth/session";
 import { db } from "@/lib/db/client";
 import { userTitleStatus } from "@/lib/db/schema";
+import {
+  getWatchCount,
+  getWatchHistory,
+  type HistoryBucket,
+  type TimePeriod,
+} from "@/lib/services/discovery";
 import { importTitle } from "@/lib/services/metadata";
 import {
   getEpisodeProgressByTmdbIds,
@@ -55,3 +62,19 @@ export async function quickAddToWatchlist(
   setTitleStatus(userId, title.id, "watchlist");
   return { success: true, titleId: title.id, alreadyAdded: false };
 }
+
+const statsSchema = z.object({
+  type: z.enum(["movies", "episodes"]),
+  period: z.enum(["today", "this_week", "this_month", "this_year"]),
+});
+
+export async function getStatsAction(
+  type: "movies" | "episodes",
+  period: TimePeriod,
+): Promise<{ count: number; history: HistoryBucket[] }> {
+  const session = await requireSession();
+  const parsed = statsSchema.parse({ type, period });
+  const count = getWatchCount(session.user.id, parsed.type, parsed.period);
+  const history = getWatchHistory(session.user.id, parsed.type, parsed.period);
+  return { count, history };
+}