refactor(ui): consolidate dialog footers + shared empty-state, unify buttons/rounding

Addresses the cross-screen inconsistencies from the layout audit by routing screens onto
the design system's own (previously under-used) shared helpers:

- Dialog footers: migrate ~9 overlay dialogs off hand-rolled placement onto the shared
  helpers — DialogActionFooter (primary+Close), DialogConfirmFooter, or
  BeginOverlayDialogFooter for custom/multi-button rows — so footers share one centered
  treatment. All footer/action buttons now use TactileButton (glass press) instead of the
  bare StyledButton some dialogs used.
- Empty states: add a shared material::DrawEmptyState(icon, title, hint) (centered icon +
  title + wrapped hint) and adopt it in Peers, Transactions, and Market-portfolio, which
  previously showed a bare left-aligned caption.
- Security dialogs: add the missing Cancel to Change Passphrase and Set PIN so the whole
  security family shares a two-button footer (Cancel dismisses without applying).
- Transactions pager: shared TactileButton helpers (matching Explorer).
- Frosted-pane rounding: Contacts/Chat use Layout::glassRounding() instead of hardcoded
  12/10/8px literals, matching Peers.
- "Set Label..." title loses its stray trailing ellipsis.

Preserves every button's label and action; the transfer footer's order becomes
[Confirm][Cancel] to match the shared helper's primary-first convention. Verified at 1280
across full-node + Lite + Windows (ctest green) and an adversarial diff review (clean).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ui/windows/transaction_details_dialog.cpp

@@ -174,25 +174,18 @@ void TransactionDetailsDialog::render(App* app)
         ImGui::Separator();
         ImGui::Spacing();
 
-        // Buttons
-        float button_width = bottomBtn.width;
-        float total_width = button_width * 2 + ImGui::GetStyle().ItemSpacing.x;
-        float start_x = (ImGui::GetWindowWidth() - total_width) / 2.0f;
-        ImGui::SetCursorPosX(start_x);
-        
+        // Buttons — centered primary + Close pair via the shared footer helper.
         // Guard against an empty/whitespace explorer URL so we never open a garbage link.
         std::string explorerBase = app->settings()->getTxExplorerUrl();
         bool explorerValid = explorerBase.find_first_not_of(" \t\r\n") != std::string::npos;
-        if (!explorerValid) ImGui::BeginDisabled();
-        if (material::StyledButton(TR("tx_view_explorer"), ImVec2(button_width, 0), S.resolveFont(bottomBtn.font))) {
+        bool doExplorer = false, doClose = false;
+        material::DialogActionFooter(TR("tx_view_explorer"), explorerValid, TR("close"),
+                                     doExplorer, doClose, bottomBtn.width);
+        if (doExplorer) {
             std::string url = explorerBase + tx.txid;
             util::Platform::openUrl(url);
         }
-        if (!explorerValid) ImGui::EndDisabled();
-        
-        ImGui::SameLine();
-        
-        if (material::StyledButton(TR("close"), ImVec2(button_width, 0), S.resolveFont(bottomBtn.font))) {
+        if (doClose) {
             s_open = false;
         }
         material::EndOverlayDialog();