feat(design): add design scheme support and UI improvements

- Implement design scheme system with palette, typography, and feature customization
- Add color scheme dialog for user customization
- Update chat UI components to use design scheme values
- Improve header actions with consolidated deploy and export buttons
- Adjust layout spacing and styling across multiple components (chat, workbench etc...)
- Add model and provider info to chat messages
- Refactor workbench and sidebar components for better responsiveness

app/components/header/Header.tsx

@@ -10,7 +10,7 @@ export function Header() {
 
   return (
     <header
-      className={classNames('flex items-center p-5 border-b h-[var(--header-height)]', {
+      className={classNames('flex items-center px-4 border-b h-[var(--header-height)]', {
         'border-transparent': !chat.started,
         'border-bolt-elements-borderColor': chat.started,
       })}
@@ -30,8 +30,8 @@ export function Header() {
           </span>
           <ClientOnly>
             {() => (
-              <div className="mr-1">
-                <HeaderActionButtons />
+              <div className="">
+                <HeaderActionButtons chatStarted={chat.started} />
               </div>
             )}
           </ClientOnly>