Polish: daily reward via celebration overlay + premium chat to recipient

- Daily reward now routes through the global CelebrationOverlay: new "daily"
  variant + coins count-up; claiming closes the daily modal and fires
  celebrate({variant:"daily", coins}). Unifies the "you earned X" moment.
- Premium (pro) gold chat is now visible to the OTHER player: ChatMessage gains
  senderPro; server resolves each participant's plan once (SocialService.IsPro)
  and stamps it on ChatMessageDto; ChatScreen styles incoming bubbles with
  .premium-chat when senderPro. Mock marks ~half its friends pro so it's visible
  offline too.

Verified: tsc + next build + dotnet build all pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/screens/ChatScreen.tsx

@@ -95,7 +95,7 @@ export function ChatScreen() {
               "max-w-[78%] rounded-2xl px-3.5 py-2 text-sm",
               m.fromMe
                 ? cn("ms-auto rounded-ee-sm", isPro ? "premium-chat" : "btn-gold")
-                : "me-auto glass text-cream rounded-es-sm"
+                : cn("me-auto rounded-es-sm", m.senderPro ? "premium-chat" : "glass text-cream")
             )}
           >
             {m.text}