Add per-user detail pages with activity chart and request history

Each user in the leaderboard links to a profile page showing stat cards,
a line chart (requests / storage / watch hours, 1W–1Y timeframes, raw or
normalized, plus a Storage Load mode), and a full request history sorted
newest-first. Includes Overseerr media status codes (1–5), Tautulli watch
history aggregation, and a server-side raw cache so the user API route can
enrich requests without re-fetching everything.

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

src/instrumentation.ts

@@ -0,0 +1,14 @@
+/**
+ * Next.js instrumentation hook — runs once when the server starts.
+ * Used to kick off the background stats poller so alerts are generated
+ * and Discord notifications are sent even when no client is connected.
+ */
+
+export async function register() {
+  // Only run in the Node.js runtime (not Edge).
+  // better-sqlite3 and the fetch clients require Node.js APIs.
+  if (process.env.NEXT_RUNTIME === "edge") return;
+
+  const { startBackgroundPoller } = await import("@/lib/statsBuilder");
+  startBackgroundPoller();
+}