feat(stats): add library entry deletion and app-wide delete progress

- Add "Delete Entry" to the anime detail view: removes every episode, session, subtitle line, rollup and cover art for a title plus the vocab counts derived from them, then drops it from the Library grid; refused while that title is currently playing.
- Show delete progress (session, session group, episode, entry) app-wide via a top progress bar + status toast that persist across tab switches, detail views, and the stats overlay window instead of going blank off-tab.
- Fix delete and Vocabulary-tab performance: store seen_ms on word/kanji occurrences so deletes subtract only removed rows via a covering index instead of rescanning each word's full history, and paginate vocab rows before aggregating anime counts.
- Migrate existing databases in place on first launch after upgrade.

stats/src/components/anime/AnimeDetailView.tsx

@@ -1,6 +1,7 @@
-import { useState, useEffect } from 'react';
+import { useState, useEffect, useRef } from 'react';
 import { useAnimeDetail } from '../../hooks/useAnimeDetail';
 import { getStatsClient } from '../../hooks/useStatsApi';
+import { confirmAnimeDelete } from '../../lib/delete-confirm';
 import { epochDayToDate } from '../../lib/formatters';
 import { AnimeHeader } from './AnimeHeader';
 import { EpisodeList } from './EpisodeList';
@@ -16,6 +17,8 @@ interface AnimeDetailViewProps {
   onBack: () => void;
   onNavigateToWord?: (wordId: number) => void;
   onOpenEpisodeDetail?: (videoId: number) => void;
+  /** Called after the whole library entry is deleted, so the caller can refresh. */
+  onAnimeDeleted?: () => void;
 }
 
 type Range = 14 | 30 | 90;
@@ -139,10 +142,14 @@ export function AnimeDetailView({
   onBack,
   onNavigateToWord,
   onOpenEpisodeDetail,
+  onAnimeDeleted,
 }: AnimeDetailViewProps) {
   const { data, loading, error, reload } = useAnimeDetail(animeId);
   const [showAnilistSelector, setShowAnilistSelector] = useState(false);
   const [coverRetryToken, setCoverRetryToken] = useState(0);
+  const [isDeletingAnime, setIsDeletingAnime] = useState(false);
+  const [deleteError, setDeleteError] = useState<string | null>(null);
+  const isDeletingAnimeRef = useRef(false);
   const knownWordsSummary = useAnimeKnownWords(animeId);
 
   useEffect(() => {
@@ -154,6 +161,37 @@ export function AnimeDetailView({
   if (!data?.detail) return <div className="text-ctp-overlay2 p-4">Anime not found</div>;
 
   const { detail, episodes, anilistEntries } = data;
+
+  const handleDeleteAnime = async () => {
+    if (isDeletingAnimeRef.current) return;
+    isDeletingAnimeRef.current = true;
+    let confirmed = false;
+    try {
+      confirmed = await confirmAnimeDelete(detail.canonicalTitle, detail.episodeCount);
+    } catch (err) {
+      setDeleteError(err instanceof Error ? err.message : 'Failed to confirm delete.');
+      isDeletingAnimeRef.current = false;
+      return;
+    }
+    if (!confirmed) {
+      isDeletingAnimeRef.current = false;
+      return;
+    }
+
+    setDeleteError(null);
+    setIsDeletingAnime(true);
+    try {
+      await getStatsClient().deleteAnime(animeId);
+      onAnimeDeleted?.();
+      onBack();
+    } catch (err) {
+      setDeleteError(err instanceof Error ? err.message : 'Failed to delete this title.');
+      setIsDeletingAnime(false);
+    } finally {
+      isDeletingAnimeRef.current = false;
+    }
+  };
+
   return (
     <div className="space-y-4">
       <button
@@ -168,7 +206,10 @@ export function AnimeDetailView({
         anilistEntries={anilistEntries ?? []}
         coverRetryToken={coverRetryToken}
         onChangeAnilist={() => setShowAnilistSelector(true)}
+        onDeleteAnime={() => void handleDeleteAnime()}
+        isDeletingAnime={isDeletingAnime}
       />
+      {deleteError ? <div className="text-sm text-ctp-red">{deleteError}</div> : null}
       <AnimeOverviewStats detail={detail} knownWordsSummary={knownWordsSummary} />
       <EpisodeList
         episodes={episodes}

stats/src/components/anime/AnimeHeader.test.tsx

@@ -0,0 +1,71 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { renderToStaticMarkup } from 'react-dom/server';
+import { AnimeHeader } from './AnimeHeader';
+import { confirmAnimeDelete, setDeleteConfirmPresenter } from '../../lib/delete-confirm';
+import type { AnimeDetailData } from '../../types/stats';
+
+const DETAIL: AnimeDetailData['detail'] = {
+  animeId: 3,
+  canonicalTitle: 'Project Radio Noise Season 2',
+  anilistId: 20661,
+  titleRomaji: 'Toaru Kagaku no Railgun S',
+  titleEnglish: 'A Certain Scientific Railgun S',
+  titleNative: null,
+  description: null,
+  totalSessions: 1,
+  totalActiveMs: 960_000,
+  totalCards: 0,
+  totalTokensSeen: 1_655,
+  totalLinesSeen: 300,
+  totalLookupCount: 0,
+  totalLookupHits: 0,
+  totalYomitanLookupCount: 0,
+  episodeCount: 1,
+  lastWatchedMs: 1_700_000_000_000,
+};
+
+test('AnimeHeader offers a delete-entry action alongside the AniList actions', () => {
+  const markup = renderToStaticMarkup(
+    <AnimeHeader detail={DETAIL} anilistEntries={[]} onDeleteAnime={() => {}} />,
+  );
+
+  assert.match(markup, /Delete Entry/);
+  assert.match(markup, /Delete this title and every session and stat recorded for it/);
+});
+
+test('AnimeHeader hides the delete action when no handler is wired', () => {
+  const markup = renderToStaticMarkup(<AnimeHeader detail={DETAIL} anilistEntries={[]} />);
+
+  assert.doesNotMatch(markup, /Delete Entry/);
+});
+
+test('AnimeHeader shows a pending state while the entry is being deleted', () => {
+  const markup = renderToStaticMarkup(
+    <AnimeHeader detail={DETAIL} anilistEntries={[]} onDeleteAnime={() => {}} isDeletingAnime />,
+  );
+
+  assert.match(markup, /disabled=""/);
+  assert.match(markup, /animate-spin/);
+  assert.doesNotMatch(markup, /Delete Entry/);
+});
+
+test('confirmAnimeDelete spells out how much data the entry deletion removes', async () => {
+  const seen: string[] = [];
+  const restore = setDeleteConfirmPresenter((message) => {
+    seen.push(message);
+    return false;
+  });
+
+  try {
+    await confirmAnimeDelete('Railgun Season 2', 1);
+    await confirmAnimeDelete('Railgun Season 2', 3);
+  } finally {
+    restore();
+  }
+
+  assert.match(seen[0] ?? '', /"Railgun Season 2"/);
+  assert.match(seen[0] ?? '', /1 episode\b/);
+  assert.match(seen[1] ?? '', /3 episodes/);
+  assert.match(seen[0] ?? '', /every session and stat/);
+});

stats/src/components/anime/AnimeHeader.tsx

@@ -6,6 +6,8 @@ interface AnimeHeaderProps {
   anilistEntries: AnilistEntry[];
   coverRetryToken?: number;
   onChangeAnilist?: () => void;
+  onDeleteAnime?: () => void;
+  isDeletingAnime?: boolean;
 }
 
 function AnilistButton({ entry }: { entry: AnilistEntry }) {
@@ -32,6 +34,8 @@ export function AnimeHeader({
   anilistEntries,
   coverRetryToken = 0,
   onChangeAnilist,
+  onDeleteAnime,
+  isDeletingAnime = false,
 }: AnimeHeaderProps) {
   const altTitles = [detail.titleRomaji, detail.titleEnglish, detail.titleNative].filter(
     (t): t is string => t != null && t !== detail.canonicalTitle,
@@ -95,6 +99,25 @@ export function AnimeHeader({
                 : 'Link to AniList'}
             </button>
           )}
+          {onDeleteAnime && (
+            <button
+              type="button"
+              onClick={onDeleteAnime}
+              disabled={isDeletingAnime}
+              title="Delete this title and every session and stat recorded for it"
+              className="inline-flex items-center gap-1 px-2 py-1 text-xs rounded bg-ctp-surface1 text-ctp-red/80 hover:bg-ctp-red/15 hover:text-ctp-red transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
+            >
+              {isDeletingAnime ? (
+                <span
+                  aria-hidden="true"
+                  className="h-3 w-3 animate-spin rounded-full border-2 border-ctp-surface2 border-t-ctp-red"
+                />
+              ) : (
+                <span aria-hidden="true">{'\u2715'}</span>
+              )}
+              {isDeletingAnime ? 'Deleting\u2026' : 'Delete Entry'}
+            </button>
+          )}
         </div>
         {detail.description && (
           <p className="text-xs text-ctp-subtext0 mt-3 line-clamp-3 leading-relaxed">

stats/src/components/anime/AnimeTab.tsx

@@ -53,7 +53,7 @@ export function AnimeTab({
   onNavigateToWord,
   onOpenEpisodeDetail,
 }: AnimeTabProps) {
-  const { anime, loading, error } = useAnimeLibrary();
+  const { anime, loading, error, reload } = useAnimeLibrary();
   const [search, setSearch] = useState('');
   const [sortKey, setSortKey] = useState<SortKey>('lastWatched');
   const [cardSize, setCardSize] = useState<LibraryCardSize>(() =>
@@ -98,6 +98,7 @@ export function AnimeTab({
             ? (videoId) => onOpenEpisodeDetail(selectedAnimeId, videoId)
             : undefined
         }
+        onAnimeDeleted={reload}
       />
     );
   }