feat: server-side romaji overrides (shared list); preload ExoPlayer from SharedPreferences on cold start

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/api.js

@@ -99,19 +99,40 @@ export async function fetchRomajiIndex() {
 export function invalidateRomajiIndex() { _romajiIndex = null; _romajiMap = null; _artistRomajiMap = null; }
 
 // ─── ROMAJI OVERRIDES ───
-// Manual kanji → romaji corrections stored in localStorage. Always take priority over auto-conversion.
+// Stored server-side (shared across all clients). Cached in memory per session.
+let _overridesCache = null; // null = not loaded yet
+
 export function getRomajiOverrides() {
-  try { return JSON.parse(localStorage.getItem('ns_romaji_overrides') || '{}'); } catch { return {}; }
+  return _overridesCache || {};
 }
-export function setRomajiOverride(kanji, romaji) {
-  const o = getRomajiOverrides();
-  if (romaji?.trim()) o[kanji.trim()] = romaji.trim(); else delete o[kanji.trim()];
-  localStorage.setItem('ns_romaji_overrides', JSON.stringify(o));
+
+export async function loadRomajiOverrides() {
+  if (!S.cfg?.backendUrl) return;
+  try {
+    const r = await fetch(`${S.cfg.backendUrl}/api/romaji-overrides`);
+    _overridesCache = r.ok ? await r.json() : {};
+  } catch { _overridesCache = {}; }
 }
-export function removeRomajiOverride(kanji) {
-  const o = getRomajiOverrides();
-  delete o[kanji];
-  localStorage.setItem('ns_romaji_overrides', JSON.stringify(o));
+
+export async function setRomajiOverride(kanji, romaji) {
+  if (!S.cfg?.backendUrl || !kanji?.trim()) return;
+  try {
+    await fetch(`${S.cfg.backendUrl}/api/romaji-overrides`, {
+      method: 'POST', headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ kanji: kanji.trim(), romaji: romaji?.trim() || '' }),
+    });
+    if (!_overridesCache) _overridesCache = {};
+    if (romaji?.trim()) _overridesCache[kanji.trim()] = romaji.trim();
+    else delete _overridesCache[kanji.trim()];
+  } catch (e) { console.warn('setRomajiOverride failed:', e); }
+}
+
+export async function removeRomajiOverride(kanji) {
+  if (!S.cfg?.backendUrl || !kanji) return;
+  try {
+    await fetch(`${S.cfg.backendUrl}/api/romaji-overrides/${encodeURIComponent(kanji)}`, { method: 'DELETE' });
+    if (_overridesCache) delete _overridesCache[kanji];
+  } catch (e) { console.warn('removeRomajiOverride failed:', e); }
 }
 
 export function dispArtistById(id, name) {