feat(stats): build anime-centric stats dashboard frontend

5-tab React dashboard with Catppuccin Mocha theme:
- Overview: hero stats, streak calendar, watch time chart, recent sessions
- Anime: grid with cover art, episode list with completion %, detail view
- Trends: 15 charts across Activity, Efficiency, Anime, and Patterns
- Vocabulary: POS-filtered word/kanji lists with detail panels
- Sessions: expandable session history with event timeline

Features:
- Cross-tab navigation (anime <-> vocabulary)
- Global word detail panel overlay
- Expandable episode detail with Anki card links (Expression field)
- Per-anime multi-line trend charts
- Watch time by day-of-week and hour-of-day
- Collapsible sections with accessibility (aria-expanded)
- Card size selector for anime grid
- Cover art caching via AniList
- HTTP API client with file:// protocol fallback for Electron overlay

stats/src/components/anime/AnimeHeader.tsx

@@ -0,0 +1,81 @@
+import { AnimeCoverImage } from './AnimeCoverImage';
+import type { AnimeDetailData, AnilistEntry } from '../../types/stats';
+
+interface AnimeHeaderProps {
+  detail: AnimeDetailData['detail'];
+  anilistEntries: AnilistEntry[];
+}
+
+function AnilistButton({ entry }: { entry: AnilistEntry }) {
+  const label = entry.season != null
+    ? `Season ${entry.season}`
+    : entry.titleEnglish ?? entry.titleRomaji ?? 'AniList';
+
+  return (
+    <a
+      href={`https://anilist.co/anime/${entry.anilistId}`}
+      target="_blank"
+      rel="noopener noreferrer"
+      className="inline-flex items-center gap-1 px-2 py-1 text-xs rounded bg-ctp-surface1 text-ctp-blue hover:bg-ctp-surface2 hover:text-ctp-sapphire transition-colors"
+    >
+      {label}
+      <span className="text-[10px]">{'\u2197'}</span>
+    </a>
+  );
+}
+
+export function AnimeHeader({ detail, anilistEntries }: AnimeHeaderProps) {
+  const altTitles = [detail.titleRomaji, detail.titleEnglish, detail.titleNative]
+    .filter((t): t is string => t != null && t !== detail.canonicalTitle);
+  const uniqueAltTitles = [...new Set(altTitles)];
+
+  const hasMultipleEntries = anilistEntries.length > 1;
+
+  return (
+    <div className="flex gap-4">
+      <AnimeCoverImage
+        animeId={detail.animeId}
+        title={detail.canonicalTitle}
+        className="w-32 h-44 rounded-lg shrink-0"
+      />
+      <div className="flex-1 min-w-0">
+        <h2 className="text-lg font-bold text-ctp-text truncate">{detail.canonicalTitle}</h2>
+        {uniqueAltTitles.length > 0 && (
+          <div className="text-xs text-ctp-overlay2 mt-0.5 truncate">
+            {uniqueAltTitles.join(' · ')}
+          </div>
+        )}
+        <div className="text-sm text-ctp-subtext0 mt-2">
+          {detail.episodeCount} episode{detail.episodeCount !== 1 ? 's' : ''}
+        </div>
+        {anilistEntries.length > 0 ? (
+          <div className="flex flex-wrap gap-1.5 mt-2">
+            {hasMultipleEntries ? (
+              anilistEntries.map((entry) => (
+                <AnilistButton key={entry.anilistId} entry={entry} />
+              ))
+            ) : (
+              <a
+                href={`https://anilist.co/anime/${anilistEntries[0]!.anilistId}`}
+                target="_blank"
+                rel="noopener noreferrer"
+                className="inline-flex items-center gap-1 px-2 py-1 text-xs rounded bg-ctp-surface1 text-ctp-blue hover:bg-ctp-surface2 hover:text-ctp-sapphire transition-colors"
+              >
+                View on AniList <span className="text-[10px]">{'\u2197'}</span>
+              </a>
+            )}
+          </div>
+        ) : detail.anilistId ? (
+          <a
+            href={`https://anilist.co/anime/${detail.anilistId}`}
+            target="_blank"
+            rel="noopener noreferrer"
+            className="inline-flex items-center gap-1 mt-2 px-2 py-1 text-xs rounded bg-ctp-surface1 text-ctp-blue hover:bg-ctp-surface2 hover:text-ctp-sapphire transition-colors"
+          >
+            View on AniList <span className="text-[10px]">{'\u2197'}</span>
+          </a>
+        ) : null}
+      </div>
+    </div>
+  );
+}