feat(covers): logo fallback for broken cover art images

CachedImage now shows /logo-psysonic.png when an image fails to load
instead of a broken icon. The fallback switches to object-fit: contain
with a card background so the logo stays proportional inside the container.

If the caller provides a custom onError (e.g. to hide the element), that
handler is used instead. A separate fallbackSrc state prevents React from
re-writing the broken URL on re-renders. The DOM-level onerror = null
guard prevents any infinite error loop.

extractCoverColors skips color extraction when the logo fallback is
active, falling back to the theme accent color instead.

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

src/utils/dynamicColors.ts

@@ -127,6 +127,8 @@ const MIN_CONTRAST    = 4.5;
  */
 export function extractCoverColors(imageUrl: string): Promise<CoverColors> {
   if (!imageUrl) return Promise.resolve({ accent: '' });
+  // Logo fallback has no meaningful color — skip extraction and use theme accent
+  if (imageUrl.includes('logo-psysonic')) return Promise.resolve({ accent: '' });
 
   return new Promise(resolve => {
     const img = new Image();