Update dependency anomalyco/opencode to v1.18.21

[vinnyang]

This PR contains the following updates:

Package	Update	Change
anomalyco/opencode	patch	1.18.20 → 1.18.21

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Release Notes

anomalyco/opencode (anomalyco/opencode)

v1.18.21

Compare Source

Core

Bugfixes

• Continue responses when a model reports an unknown finish reason instead of stopping early
• Route Vertex AI eu and us multi-region Gemini requests through REP endpoints

Desktop

Bugfixes

• Keep file search results visible while the next search is loading
• Register the archive session command in both desktop layouts (@​NathanTCode)

Thank you to 1 community contributor:

• @​NathanTCode:
  • fix(app): register archive session command in both layouts (#​41741)

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