Replace server actions with API routes and add SWR data-fetching hooks

- Convert discover, stats, status, and system-health server actions to
  proper API route handlers under `app/api/`; delete `lib/actions/explore.ts`,
  `lib/actions/settings.ts`, and `lib/actions/setup.ts`
- Add `use-discover`, `use-stats`, and `use-system-health` SWR hooks
  that call the new routes; update `command-palette`, `title-card`,
  `update-toast`, and `stats-display` to consume them
- Lift auth centering wrapper from individual login/register pages into
  `(auth)/layout.tsx`; switch both pages from `auth.api.getSession` to
  the cached `getSession()` helper
- Relocate setup wizard from `app/(auth)/setup/` to `app/setup/` (outside
  auth group) with dedicated `copy-button` and `refresh-button` client
  components
- Move `not-found.tsx` and `error.tsx` to app root so they apply
  globally instead of only within the pages route group

lib/actions/explore.ts

@@ -1,35 +0,0 @@
-"use server";
-
-import { requireSession } from "@/lib/auth/session";
-import { discover } from "@/lib/tmdb/client";
-import { tmdbImageUrl } from "@/lib/tmdb/image";
-
-export async function discoverByGenre(
-  mediaType: "movie" | "tv",
-  genreId: number,
-) {
-  await requireSession();
-  const results = await discover(mediaType, {
-    sort_by: "popularity.desc",
-    "vote_count.gte": "50",
-    with_genres: String(genreId),
-  });
-  // Discover may return movie (title, release_date) or TV (name, first_air_date)
-  // fields depending on mediaType. The schema types them separately, so widen.
-  type DiscoverResult = NonNullable<typeof results.results>[number] & {
-    title?: string;
-    name?: string;
-    release_date?: string;
-    first_air_date?: string;
-  };
-  return ((results.results ?? []) as DiscoverResult[])
-    .filter((r) => r.poster_path)
-    .map((r) => ({
-      tmdbId: r.id,
-      type: mediaType,
-      title: r.title ?? r.name ?? "",
-      posterPath: tmdbImageUrl(r.poster_path ?? null, "posters"),
-      releaseDate: r.release_date ?? r.first_air_date ?? null,
-      voteAverage: r.vote_average,
-    }));
-}

lib/actions/settings.ts

@@ -19,14 +19,6 @@ import {
   restoreFromBackup,
 } from "@/lib/services/backup";
 import { getSetting, setSetting } from "@/lib/services/settings";
-import {
-  getSystemHealth,
-  type SystemHealthData,
-} from "@/lib/services/system-health";
-import {
-  getCachedUpdateCheck,
-  type UpdateCheckResult,
-} from "@/lib/services/update-check";
 
 const providerSchema = z.enum(["plex", "jellyfin", "emby", "sonarr", "radarr"]);
 
@@ -222,13 +214,6 @@ export async function setBackupScheduleAction(
   rescheduleBackup();
 }
 
-// --- System health actions ---
-
-export async function getSystemHealthAction(): Promise<SystemHealthData> {
-  await requireAdmin();
-  return getSystemHealth();
-}
-
 // --- Job trigger action ---
 
 export async function triggerJobAction(
@@ -256,17 +241,6 @@ export async function restoreBackupAction(formData: FormData): Promise<void> {
   await restoreFromBackup(buffer);
 }
 
-// --- Update check action ---
-
-export async function getUpdateCheckAction(): Promise<UpdateCheckResult | null> {
-  try {
-    await requireAdmin();
-    return getCachedUpdateCheck();
-  } catch {
-    return null;
-  }
-}
-
 // --- Avatar actions ---
 
 const MAX_AVATAR_SIZE = 2 * 1024 * 1024; // 2MB

lib/actions/setup.ts

@@ -1,7 +0,0 @@
-"use server";
-
-import { isTmdbConfigured } from "@/lib/config";
-
-export async function checkTmdbConfigured() {
-  return isTmdbConfigured();
-}

lib/actions/watchlist.ts

@@ -1,38 +1,11 @@
 "use server";
 
 import { and, eq } from "drizzle-orm";
-import { z } from "zod";
-import { getSession, requireSession } from "@/lib/auth/session";
+import { 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 { getOrFetchTitleByTmdbId } from "@/lib/services/metadata";
-import {
-  getEpisodeProgressByTmdbIds,
-  getUserStatusesByTmdbIds,
-  setTitleStatus,
-} from "@/lib/services/tracking";
-
-export async function fetchUserStatuses(
-  tmdbIds: { tmdbId: number; type: string }[],
-): Promise<Record<string, "watchlist" | "in_progress" | "completed">> {
-  const session = await getSession();
-  if (!session) return {};
-  return getUserStatusesByTmdbIds(session.user.id, tmdbIds);
-}
-
-export async function fetchEpisodeProgress(
-  tmdbIds: { tmdbId: number; type: string }[],
-): Promise<Record<string, { watched: number; total: number }>> {
-  const session = await getSession();
-  if (!session) return {};
-  return getEpisodeProgressByTmdbIds(session.user.id, tmdbIds);
-}
+import { setTitleStatus } from "@/lib/services/tracking";
 
 export async function quickAddToWatchlist(
   tmdbId: number,
@@ -62,19 +35,3 @@ 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 };
-}