fix(opencode): revert from the first removed assistant message - #9924

1. browse_code — apps/server/src/provider/Layers/OpenCodeAdapter.ts

2. browse_code — apps/server/src/provider/Layers/OpenCodeAdapter.ts

💭 I'm checking the changed lines for readThread and rollbackThread to see if they follow existing conventions like the error mapper and adapter shape interface, both of which predate this PR, and now I'm looking at how they use runOpenCodeSdk. The error mapping pattern matches existing code, no lint suppressions or new error types are introduced, and tests were updated appropriately using test layers for the external service. Since the diff only touches these two files with no service convention violations, I'm confident the review outcome is "All clear" and will finalize that as the summary.