Add better theme support and update marketing page layout

The theme property was added to the RootProvider component. This allows the application to initially load the theme stored in the user's cookies. The marketing page layout has been updated: images were resized, a billing section was added, and heading styles were adjusted. Text strings were also revised for clarity.

apps/web/components/root-providers.tsx

@@ -33,9 +33,11 @@ const CaptchaTokenSetter = dynamic(async () => {
 
 export function RootProviders({
   lang,
+  theme = appConfig.theme,
   children,
 }: React.PropsWithChildren<{
   lang: string;
+  theme?: string;
 }>) {
   const i18nSettings = getI18nSettings(lang);
 
@@ -51,7 +53,7 @@ export function RootProviders({
                 attribute="class"
                 enableSystem
                 disableTransitionOnChange
-                defaultTheme={appConfig.theme}
+                defaultTheme={theme}
               >
                 {children}
               </ThemeProvider>