feat: add search and favorites to model selection dropdown

[Claude]

Summary

• Adds fuzzy search input at top of model dropdown with auto-focus on open
• Implements star-based favorites system with localStorage persistence (harnss-favorite-models)
• Favorites sort to top; search filters by label/description with relevance scoring
• Wider dropdown (320px) accommodates search bar and star icons

Type of Change

• ✨ New feature (non-breaking change that adds functionality)
• 🎨 UI / design improvement

How to Test

1. Open model dropdown in input bar
2. Type to search models (fuzzy matches label/description)
3. Click star icon to favorite a model
4. Close and reopen dropdown to verify favorites persist and appear at top
5. Test with long model lists (e.g., OpenCode provider)

Screenshots / Screen Recording

Checklist

• I've tested this on macOS (required for Electron/native features)
• TypeScript compiles with no errors (pnpm build)
• No any types introduced
• Logical margins used (ms-*/me-* instead of ml-*/mr-*)
• User-generated content containers have wrap-break-word
• New shared types go in shared/types/, not src/types/
• Large components/hooks are decomposed into sub-components/sub-hooks if needed

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Feature]: Add search for model selection</issue_title>
<issue_description>### Problem / Motivation

In some situations, the model list can get quite long, especially when using the OpenCode

Proposed Solution

There should be an option to search and filter through the models. Would be a huge time saver for users using providers like OpenCode or perhaps Github Copilot

A plus could be to even have some sort of favoriting system to highlight models you frequently use (perhaps starring them) for quicker access.

Alternatives Considered

Currently when pressing anything on the keyboard while the model list is active, it would auto highlight a model and pressing the same key multiple times for basic keyboard navigation, this could be replaced with simply pressing tab which at the moment doesn't do anything when the model list is active

Area

UI / Layout / Design

Relevant Engine

Not engine-specific

How important is this to you?

Nice to have

Contribution

• I'd be willing to submit a PR for this feature

Additional Context

No response</issue_description>

Comments on the Issue (you are @claude[agent] in this section)

• Fixes [Feature]: Add search for model selection #32