Build OverSnitch dashboard

Full implementation on top of the Next.js scaffold:

- Leaderboard with per-user request count, storage, avg GB/req, and
  optional Tautulli watch stats (plays, watch hours), each with dense
  per-metric rank (#N/total)
- SWR cache on /api/stats (5-min stale, force-refresh via button);
  client-side localStorage seed so the UI is instant on return visits
- Alerting system: content-centric alerts (unfulfilled downloads,
  partial TV downloads, stale pending requests) and user-behavior
  alerts (ghost requester, low watch rate, declined streak)
- Partial TV detection: flags ended series with <90% of episodes on disk
- Alert persistence in data/alerts.json with open/closed state,
  auto-resolve when condition clears, manual close with per-category
  cooldown, and per-alert notes
- Alert detail page rendered as a server component for instant load
- Dark UI with Tailwind v4, severity-colored left borders, summary
  cards with icons, sortable leaderboard table

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/radarr.ts

@@ -0,0 +1,19 @@
+import { RadarrMovie, MediaEntry } from "@/lib/types";
+
+export async function buildRadarrMap(): Promise<Map<number, MediaEntry>> {
+  const res = await fetch(`${process.env.RADARR_URL}/api/v3/movie`, {
+    headers: { "X-Api-Key": process.env.RADARR_API! },
+  });
+
+  if (!res.ok) {
+    throw new Error(`Radarr API error: ${res.status} ${res.statusText}`);
+  }
+
+  const movies: RadarrMovie[] = await res.json();
+  return new Map(
+    movies.map((m) => [
+      m.tmdbId,
+      { title: m.title, sizeOnDisk: m.sizeOnDisk, available: m.isAvailable },
+    ])
+  );
+}