feat(vscode): persist model selector expand/collapse state

[johnnyeric]

Context

The model picker preview panel expand/collapse state reset when the VS Code webview reloaded, hid/shown, or restarted. Persisting this preference keeps the picker in the user's chosen layout.

Implementation

Save the preview-panel expand/collapse preference through the VS Code webview state API and restore it when the model picker initializes.

Screenshots / Video

N/A. Behavior-only persistence change; no visual layout change.

How to Test

Manual/local verification

• Agent ran bun turbo typecheck via the pre-push hook.

Reviewer test steps

1. Open the VS Code extension model picker.
2. Expand or collapse the preview panel.
3. Hide/show the webview, reload the extension host, or restart VS Code.
4. Reopen the model picker and confirm the preview panel keeps the prior state.

Checklist

• Issue linked above, or exception explained
• Tests/verification described
• Screenshots/video included for visual changes, or marked N/A
• Changeset considered for user-facing changes
• I personally reviewed the diff and can explain the changes, including any AI-assisted work.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (2 files)

• packages/kilo-vscode/webview-ui/src/components/shared/ModelSelector.tsx
• packages/kilo-vscode/webview-ui/src/context/vscode.tsx

Previous Review Summary (commit c5aec20)

Current summary above is authoritative. Previous snapshots are kept for context only.

Previous review (commit c5aec20)

Status: No Issues Found | Recommendation: Merge

Files Reviewed (2 files)

• .changeset/persist-model-picker-state.md
• packages/kilo-vscode/webview-ui/src/components/shared/ModelSelector.tsx

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