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/library/MediaSessionList.tsx

@@ -0,0 +1,40 @@
+import { formatDuration, formatRelativeDate, formatNumber } from '../../lib/formatters';
+import type { SessionSummary } from '../../types/stats';
+
+interface MediaSessionListProps {
+  sessions: SessionSummary[];
+}
+
+export function MediaSessionList({ sessions }: MediaSessionListProps) {
+  if (sessions.length === 0) {
+    return <div className="text-sm text-ctp-overlay2">No sessions recorded</div>;
+  }
+
+  return (
+    <div className="space-y-2">
+      <h3 className="text-sm font-semibold text-ctp-text">Session History</h3>
+      {sessions.map((s) => (
+        <div
+          key={s.sessionId}
+          className="bg-ctp-surface0 border border-ctp-surface1 rounded-lg p-3 flex items-center justify-between"
+        >
+          <div className="min-w-0">
+            <div className="text-sm text-ctp-text">
+              {formatRelativeDate(s.startedAtMs)} · {formatDuration(s.activeWatchedMs)} active
+            </div>
+          </div>
+          <div className="flex gap-4 text-xs text-center shrink-0">
+            <div>
+              <div className="text-ctp-green font-medium">{formatNumber(s.cardsMined)}</div>
+              <div className="text-ctp-overlay2">cards</div>
+            </div>
+            <div>
+              <div className="text-ctp-mauve font-medium">{formatNumber(s.wordsSeen)}</div>
+              <div className="text-ctp-overlay2">words</div>
+            </div>
+          </div>
+        </div>
+      ))}
+    </div>
+  );
+}