fix(settings): drop dead bottom padding below the action bar

`--settings-action-bar-space: 80px` added padding-bottom to the form
*after* its last child (the action bar), giving 80px of scrollable
empty space below the bar — visible when scrolling to the end as a
big dark band the page kept scrolling past the last setting.

The reservation was originally tuned for the OLD floating-chip
layout, where the bar hovered 24px above the bottom edge and content
needed to be pushed above it. In the new sticky-footer model the bar
IS the bottom edge, so no padding is needed below it.

Set to 0px. CDP verifies form.bottom === bar.bottom after the change
— the scroll now ends cleanly at the action bar.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/src/_settings-theme.scss

@@ -5,7 +5,15 @@
     // previous 24px gap was tuned for the old floating-chip layout where
     // the bar visually hovered above the bottom.
     --settings-action-bar-offset: 0px;
-    --settings-action-bar-space: 112px;
+    // 0 by default — the action bar is now the last child of the form
+    // and acts as the natural bottom edge, so no padding-bottom is
+    // needed below it. The previous 112px/80px reservation existed to
+    // push content above the OLD floating-chip layout, but in the new
+    // sticky-footer model that just added dead scrollable space below
+    // the last setting row. The bar's own padding (12px) and the
+    // section title bottom-borders already provide visual breathing
+    // room when scrolled to the end.
+    --settings-action-bar-space: 0px;
     --settings-page-header-bg: color-mix(
         in srgb,
         var(--mat-sys-surface-container-low) 94%,