style(dashboard): make home page container responsive padding

Adjust AppShell padding to responsive values and add a CSS module that
handles container top and side padding for different breakpoints,
replacing the previous fixed `pt="xl"` usage.

apps/client/src/components/layouts/global/global-app-shell.tsx

@@ -99,7 +99,7 @@ export default function GlobalAppShell({
           collapsed: { mobile: !isAsideOpen, desktop: !isAsideOpen },
         }
       }
-      padding="md"
+      padding={{ base: "xs", sm: "md" }}
     >
       <AppShell.Header px="md" className={classes.header}>
         <AppHeader />