perf(web): improve dialog sizing and footer layout

- migrate frontend dialogs to the shared footer API so actions stay separated from scrollable body content.
- tune dialog dimensions for model analytics, prefill groups, billing history, channel model sync, and related workflows.
- update channel terminology and dialog action translations across supported locales.

web/default/src/components/dialog.tsx

@@ -54,7 +54,7 @@ export function Dialog({
   children,
   trigger,
   footer,
-  contentHeight = 'min(58vh, 520px)',
+  contentHeight = 'auto',
   contentClassName,
   headerClassName,
   titleClassName,