fix: use stable provider key for logo v-for loop

Replace unstable index-based key with logo.provider for reliable
DOM tracking when logo order changes.

Amp-Thread-ID: https://ampcode.com/threads/T-019c083e-8ba0-7699-a5ff-63fd03e24391
Co-authored-by: Amp <amp@ampcode.com>

src/components/templates/thumbnails/LogoOverlay.vue

@@ -1,7 +1,7 @@
 <template>
   <div
-    v-for="(logo, index) in validLogos"
-    :key="index"
+    v-for="logo in validLogos"
+    :key="logo.provider"
     :class="
       cn('pointer-events-none absolute z-10', logo.position ?? defaultPosition)
     "