fix(settings): lower page-masonry threshold so it engages under display scaling

The 1000-logical-px threshold never engaged at 125% OS scaling: the panel's
real-px width (~1190) was below 1000×dpiScale (~1250), so the page stayed
single-column even though the internal NODE & SECURITY two-column (760×dpiScale)
did engage. Drop to 780 logical px — still requires usable (~390 logical) columns
but engages at the widths real windows actually have under display scaling.

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

src/ui/pages/settings_page.cpp

@@ -654,7 +654,10 @@ void RenderSettingsPage(App* app) {
     // ====================================================================
     const float msFullWidth = availWidth;
     const float msColGap = Layout::spacingXl();
-    const bool  msTwoCol = availWidth > 1000.0f * Layout::dpiScale();
+    // Threshold is in logical px (× dpiScale): two columns once each is usable
+    // (~390 logical wide). Kept low enough to engage under OS display scaling,
+    // where the panel's real-px width is smaller in logical terms.
+    const bool  msTwoCol = availWidth > 780.0f * Layout::dpiScale();
     const float msColW = msTwoCol ? (msFullWidth - msColGap) * 0.5f : msFullWidth;
     const ImVec2 msColTop = ImGui::GetCursorPos();
     float msLeftBottomY = 0.0f;