perf(server): stop retaining unused OpenCode tool history - #9684

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✅ Gathered PR context (5s)
✅ Completed bug detection (1m 30s)
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Final Result: Bugbot completed review - no issues found! ✅

Request ID: serverGenReqId_3b4e0a67-d8bf-4e3f-b853-0aeaae1f5994