fix(hidpi): scale security-dialog buttons, market caption, QR inset by dpiScale

HiDPI geometry debt from the audit: 15 security-dialog buttons used a raw 40px
height (undersized vs the scaled label at 1.5x), the market "Updated" caption
used a raw SameLine(0,12), and the QR popup's 28px overlay-inset budget wasn't
scaled (wrapping the address at HiDPI). All now go through ui::Layout::dpiScale().

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

src/ui/windows/market_tab.cpp

@@ -1431,7 +1431,7 @@ static void mktDrawPairSelector(App* app, const std::vector<data::ExchangeInfo>&
         ImGui::Dummy(ImVec2(0, Layout::spacingSm()));
         Type().textColored(TypeStyle::Caption, OnSurfaceDisabled(), TR("market_attribution"));
         if (!market.last_updated.empty()) {
-            ImGui::SameLine(0, 12);
+            ImGui::SameLine(0, 12.0f * Layout::dpiScale());
             snprintf(buf, sizeof(buf), TR("market_updated"), market.last_updated.c_str());
             Type().textColored(TypeStyle::Caption, OnSurfaceDisabled(), buf);
         }

src/ui/windows/qr_popup_dialog.cpp

@@ -74,7 +74,9 @@ void QRPopupDialog::render(App* app)
     const float addrBoxW = ImGui::CalcTextSize(chunkedAddr.c_str()).x + addrPadX * 2.0f + 2.0f;
     // The BlurFloat overlay card insets content by 28px per side (draw_helpers BeginOverlayDialog); add
     // that (+ a little slack) so the address box fits on one line under its label instead of wrapping.
-    const float wantW    = addrBoxW + 28.0f * 2.0f + 12.0f;
+    // Scale the overlay inset (BeginOverlayDialog insets 28 LOGICAL px/side) into the same scaled space
+    // as addrBoxW before the /dp conversion below, so the address box doesn't wrap at HiDPI.
+    const float wantW    = addrBoxW + (28.0f * 2.0f + 12.0f) * dp;
     const float maxW     = 0.85f * ImGui::GetMainViewport()->Size.x;
     const float cardW    = (wantW < maxW ? wantW : maxW) / dp;
     material::OverlayDialogSpec ov;