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>

.automaker/categories.json

@@ -3,5 +3,6 @@
   "Core",
   "Kanban",
   "Other",
-  "Settings"
+  "Settings",
+  "Uncategorized"
 ]