feat: overhaul stats dashboard with navigation, trends, and anime views

Add navigation state machine for tab/detail routing, anime overview
stats with Yomitan lookup rates, session word count accuracy fixes,
vocabulary tab hook order fix, simplified trends data fetching from
backend-aggregated endpoints, and improved session detail charts.

stats/src/lib/stats-ui-navigation.test.tsx

@@ -0,0 +1,40 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { renderToStaticMarkup } from 'react-dom/server';
+import { TabBar } from '../components/layout/TabBar';
+import { EpisodeList } from '../components/anime/EpisodeList';
+
+test('TabBar renders Library instead of Anime for the media library tab', () => {
+  const markup = renderToStaticMarkup(<TabBar activeTab="overview" onTabChange={() => {}} />);
+
+  assert.doesNotMatch(markup, />Anime</);
+  assert.match(markup, />Overview</);
+  assert.match(markup, />Library</);
+});
+
+test('EpisodeList renders explicit episode detail button alongside quick peek row', () => {
+  const markup = renderToStaticMarkup(
+    <EpisodeList
+      episodes={[
+        {
+          videoId: 9,
+          episode: 9,
+          season: 1,
+          durationMs: 1,
+          watched: 0,
+          canonicalTitle: 'Episode 9',
+          totalSessions: 1,
+          totalActiveMs: 1,
+          totalCards: 1,
+          totalWordsSeen: 350,
+          totalYomitanLookupCount: 7,
+          lastWatchedMs: 0,
+        },
+      ]}
+      onOpenDetail={() => {}}
+    />,
+  );
+
+  assert.match(markup, />Details</);
+  assert.match(markup, /Episode 9/);
+});