perf(search): use CachedImage for result thumbs to stop re-render download storms (#245)

The sidebar LiveSearch and mobile search overlay rendered cover thumbs via
raw <img src={buildCoverArtUrl(...)}> instead of going through the
IndexedDB-backed CachedImage path used everywhere else in the app.

buildCoverArtUrl() mints a fresh URL on every call (random salt + a new
MD5 token per Subsonic spec), so the browser cache was permanently
defeated for these thumbs — every re-render of the dropdown produced
new URLs and the browser dispatched HTTP requests for every "new"
image.

While typing in the search field this multiplied: each keystroke
triggered a re-render with fresh URLs for every visible cover, and
after the 300 ms debounce a fresh search() result triggered another
wave. Five visible album thumbs × five keystrokes ≈ 50 redundant cover
fetches in 1.5 s, manifesting as periodic typing delays.

Switch all three call sites to CachedImage with the stable
coverArtCacheKey() — same pattern CLAUDE.md explicitly recommends:

    buildCoverArtUrl() generates a new ephemeral URL every call —
    browser cache is useless. Use coverArtCacheKey(id, size) +
    CachedImage for <img> tags.

Confirmed locally: typing in the search field is noticeably smoother.

Co-authored-by: Psychotoxical <dev@psysonic.app>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/MobileSearchOverlay.tsx

@@ -2,10 +2,11 @@ import React, { useState, useEffect, useRef, useCallback } from 'react';
 import { createPortal } from 'react-dom';
 import { useNavigate } from 'react-router-dom';
 import { X, Search, Disc3, Users, Music, Music2, Clock, ChevronRight } from 'lucide-react';
-import { search, SearchResults, buildCoverArtUrl } from '../api/subsonic';
+import { search, SearchResults, buildCoverArtUrl, coverArtCacheKey } from '../api/subsonic';
 import { usePlayerStore, songToTrack } from '../store/playerStore';
 import { useAuthStore } from '../store/authStore';
 import { useTranslation } from 'react-i18next';
+import CachedImage from './CachedImage';
 
 const STORAGE_KEY = 'psysonic_recent_searches';
 const MAX_RECENT = 6;
@@ -203,7 +204,12 @@ export default function MobileSearchOverlay({ onClose }: { onClose: () => void }
                 {results!.albums.map(a => (
                   <button key={a.id} className="mobile-search-item" onClick={() => goTo(`/album/${a.id}`)}>
                     {a.coverArt ? (
-                      <img className="mobile-search-thumb" src={buildCoverArtUrl(a.coverArt, 80)} alt="" loading="lazy" />
+                      <CachedImage
+                        className="mobile-search-thumb"
+                        src={buildCoverArtUrl(a.coverArt, 80)}
+                        cacheKey={coverArtCacheKey(a.coverArt, 80)}
+                        alt=""
+                      />
                     ) : (
                       <div className="mobile-search-avatar">
                         <Disc3 size={20} />
@@ -225,7 +231,12 @@ export default function MobileSearchOverlay({ onClose }: { onClose: () => void }
                 {results!.songs.map(s => (
                   <button key={s.id} className="mobile-search-item" onClick={() => playSong(s)}>
                     {s.coverArt ? (
-                      <img className="mobile-search-thumb" src={buildCoverArtUrl(s.coverArt, 80)} alt="" loading="lazy" />
+                      <CachedImage
+                        className="mobile-search-thumb"
+                        src={buildCoverArtUrl(s.coverArt, 80)}
+                        cacheKey={coverArtCacheKey(s.coverArt, 80)}
+                        alt=""
+                      />
                     ) : (
                       <div className="mobile-search-avatar">
                         <Music size={20} />