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/session-detail.test.tsx

@@ -0,0 +1,32 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { renderToStaticMarkup } from 'react-dom/server';
+import { SessionDetail } from '../components/sessions/SessionDetail';
+
+test('SessionDetail omits the misleading new words metric', () => {
+  const markup = renderToStaticMarkup(
+    <SessionDetail
+      session={{
+        sessionId: 7,
+        canonicalTitle: 'Episode 7',
+        videoId: 7,
+        animeId: null,
+        animeTitle: null,
+        startedAtMs: 0,
+        endedAtMs: null,
+        totalWatchedMs: 0,
+        activeWatchedMs: 0,
+        linesSeen: 12,
+        wordsSeen: 24,
+        tokensSeen: 24,
+        cardsMined: 0,
+        lookupCount: 0,
+        lookupHits: 0,
+        yomitanLookupCount: 0,
+      }}
+    />,
+  );
+
+  assert.match(markup, /Total words/);
+  assert.doesNotMatch(markup, /New words/);
+});