[DeckShare] Open shared decks via links with a gated preview flow

- Serialized url-chain dispatcher in IntentUrlParser; queue-drained
  urlChainFinished(bool) drives the startup auto-connect fallback
- Open-shared-deck intent with sequential download state machine,
  15s per-item timeout, partial-success offer, livable Cancel via
  ApplicationModal dlg_login_prompt interactive fallback
- Preview dialog: download progress label, share vocab sweep,
  palette-highlight selection frame, Space/Enter keyboard toggle,
  NoFocus checkbox, double-click tile opens immediately
- Confirm-before-server-migration with one-shot restore to the
  previous server on failed/cancelled chains (statusChanged settle
  deferral), hostname-only identity comparisons
- Skip credential link when already connected; arrow-key navigation
  in FlowWidget; card glows use palette highlight
- Address code-review M1-M4 and UI/UX QA blockers 1-2

cockatrice/src/interface/intents/intent_join_server_game.cpp

@@ -19,13 +19,10 @@ bool IntentJoinServerGame::checkPrecondition() const
     if (remoteClient->getStatus() != ClientStatus::StatusLoggedIn) {
         return false;
     }
-    // peerPort() reflects the actual TCP peer, which may differ from the
-    // configured server port (e.g. when connecting through a proxy), so only
-    // the hostname is compared here.
-    if (remoteClient->peerName() != context->roomContext.serverContext.hostname) {
-        return false;
-    }
-    if (QString::number(remoteClient->peerPort()) != context->roomContext.serverContext.port) {
+    // serverName() reflects the server the client was configured to connect to,
+    // which may differ from the actual TCP peer (e.g. when connecting through a
+    // proxy), so only the hostname is compared here.
+    if (remoteClient->serverName().compare(context->roomContext.serverContext.hostname, Qt::CaseInsensitive) != 0) {
         return false;
     }