Drop tile shadow instead of switching to drop-shadow-sm

drop-shadow-sm (previous commit) didn't fix the corner artifact in
testing, so revert to the simplest option instead of chasing which
rasterization path is actually at fault: video tiles just don't get
an offset shadow. Border stays.

Reverts the --drop-shadow-* token additions in base.css/clay.css/
navy.css from the previous commit since nothing else used them.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

pnpm-workspace.yaml

@@ -16,14 +16,4 @@ minimumReleaseAgeExclude:
   - '@welshman/store'
   - '@welshman/util'
 overrides:
-  '@welshman/app': link:../welshman/packages/app
-  '@welshman/content': link:../welshman/packages/content
-  '@welshman/domain': link:../welshman/packages/domain
-  '@welshman/editor': link:../welshman/packages/editor
-  '@welshman/feeds': link:../welshman/packages/feeds
-  '@welshman/lib': link:../welshman/packages/lib
-  '@welshman/net': link:../welshman/packages/net
-  '@welshman/signer': link:../welshman/packages/signer
-  '@welshman/store': link:../welshman/packages/store
-  '@welshman/util': link:../welshman/packages/util
   sharp: ^0.35.3

src/app/components/VideoCallContent.svelte

@@ -221,7 +221,7 @@
   {@const media = $mediaStateByIdentity(tile.liveKitIdentity)}
   <div
     class={cx(
-      "relative isolate overflow-hidden rounded-2xl shadow-sm",
+      "relative isolate overflow-hidden rounded-2xl 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",
@@ -248,7 +248,7 @@
       </div>
     {/if}
     <span
-      class="pointer-events-none absolute bottom-1 left-1 max-w-[calc(100%-0.5rem)] truncate rounded bg-surface/80 px-1.5 py-0.5 text-xs">
+      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}