PR-C0: remove tile.track conditional — consistent border + label on all tiles

- Remove the tile.track ternary from the name label class — use bg-backdrop/80
  consistently for all tiles (both video and no-video)
- Remove the !tile.track conditional from the border — apply border border-line
  to all tiles consistently
- Fixes shadow rendering inconsistency: with two tiles, the conditional border
  + ternary caused asymmetric shadow rendering (cropped/pointed shadows)

Per review feedback from @matt on PR #3 (forgejo).

src/app/components/VideoCallContent.svelte

@@ -221,8 +221,7 @@
   {@const media = $mediaStateByIdentity(tile.liveKitIdentity)}
   <div
     class={cx(
-      "relative isolate overflow-hidden rounded-2xl shadow-sm",
-      !tile.track && "border border-line border-solid",
+      "relative isolate overflow-hidden rounded-2xl shadow-sm border border-line",
       layout === "spotlight" && "min-h-0 flex-1",
       layout === "default" && "aspect-video w-full min-h-0",
       layout === "strip" && "aspect-video w-44 shrink-0",
@@ -249,9 +248,7 @@
       </div>
     {/if}
     <span
-      class="pointer-events-none absolute bottom-1 left-1 max-w-[calc(100%-0.5rem)] truncate rounded px-1.5 py-0.5 text-xs {tile.track
-        ? 'bg-surface/80'
-        : 'bg-backdrop/80'}">
+      class="pointer-events-none absolute bottom-1 left-1 max-w-[calc(100%-0.5rem)] truncate rounded bg-backdrop/80 px-1.5 py-0.5 text-xs">
       {labelFor(tile.liveKitIdentity, tile.source)}{tile.isLocal ? " (you)" : ""}
     </span>
     {#if videoTiles.length > 1}