feat: opencode release v1.18.3

[github-actions]

What's Changed

Core

Improvements

• Added an Up Arrow shortcut to close the subagent picker when the first item is selected.

Desktop

Bugfixes

• Fixed home page scrolling so sticky headers and the session list behave correctly.
• Fixed startup readiness so WSL server loading is included before the desktop app reports ready.
• Removed the inactive help button from the app layout.
• Fixed custom agent selector visibility when custom agents are available.

Improvements

• Home page command palette search can now find and open sessions.

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Full Changelog: https://github.com/anomalyco/opencode/releases/tag/v1.18.3

This PR was created automatically by a scheduled workflow.