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/qr_popup_dialog.cpp

@@ -120,8 +120,10 @@ void QRPopupDialog::render(App* app)
         widgets::AddressCopyField("##QRAddress", s_address);
         
         ImGui::Spacing();
-        
-        // Buttons — size each to its label (so "Copy address" never clips), then center the pair.
+
+        // Footer — a primary "Copy address" + "Close" pair, placed via the shared design-system helper.
+        // Size both buttons to the wider label (so "Copy address" never clips) and hand that width to
+        // DialogActionFooter, which centers the pair.
         ImFont* btnFont = S.resolveFont(actionBtn.font);
         ImGui::PushFont(btnFont);
         const float btnPad = ImGui::GetStyle().FramePadding.x * 2.0f + 24.0f;
@@ -130,14 +132,14 @@ void QRPopupDialog::render(App* app)
         ImGui::PopFont();
         if (w_copy  < actionBtn.width) w_copy  = actionBtn.width;
         if (w_close < actionBtn.width) w_close = actionBtn.width;
-        const float total_width = w_copy + w_close + ImGui::GetStyle().ItemSpacing.x;
-        ImGui::SetCursorPosX((window_width - total_width) / 2.0f);
+        const float btnW = (w_copy > w_close ? w_copy : w_close);
 
-        if (material::TactileButton(TR("copy_address"), ImVec2(w_copy, 0), btnFont)) {
+        bool doCopy = false, doClose = false;
+        material::DialogActionFooter(TR("copy_address"), true, TR("close"), doCopy, doClose, btnW);
+        if (doCopy) {
             ImGui::SetClipboardText(s_address.c_str());
         }
-        ImGui::SameLine();
-        if (material::TactileButton(TR("close"), ImVec2(w_close, 0), btnFont)) {
+        if (doClose) {
             close();
         }
         material::EndOverlayDialog();