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/store/app-store.ts

@@ -84,10 +84,7 @@ export type OpenAIModel =
   | "gpt-5.1-codex-max"
   | "gpt-5.1-codex"
   | "gpt-5.1-codex-mini"
-  | "gpt-5.1"
-  | "o3"
-  | "o3-mini"
-  | "o4-mini";
+  | "gpt-5.1";
 // Combined model type
 export type AgentModel = ClaudeModel | OpenAIModel;