feat(ui): improve modal UX and model management

- Increase dialog max-width to 2xl for better content display
- Add tabbed interface to feature modal (prompt/model/testing)
- Streamline model selection with compact button layout
- Remove unused OpenAI O3/O4 models from registry
- Add model string validation and fallback logic
- Add "Uncategorized" category support

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4 <noreply@anthropic.com>

app/src/components/ui/dialog.tsx

@@ -63,7 +63,7 @@ function DialogContent({
         data-slot="dialog-content"
         className={cn(
           "bg-background data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 fixed top-[50%] left-[50%] z-50 flex flex-col w-full max-w-[calc(100%-2rem)] translate-x-[-50%] translate-y-[-50%] rounded-lg border shadow-lg duration-200 max-h-[calc(100vh-4rem)]",
-          compact ? "max-w-md p-4" : "sm:max-w-lg p-6",
+          compact ? "max-w-2xl p-4" : "sm:max-w-2xl p-6",
           className
         )}
         {...props}