fix(opencode): bound publish fallback timeout

[seonghobae]

Summary

• Keep the new bounded/dynamic OpenCode model-pool cadence from current main intact.
• Fix the publish-stage fallback model invocation default from 5400s to 120s so a missing env var cannot reintroduce a 90-minute stall in the approval publication path.
• Add a contract assertion for the 120s fallback default.

Reason

Current PR review runs have been accumulating in Run OpenCode PR Review model pool / publish fallback paths. Main already shortened the primary model pool; this PR removes the remaining long fallback default so failures leave a bounded, visible reason in logs.

Verification

• py -3 -m pytest tests/test_opencode_agent_contract.py tests/test_opencode_model_pool_runner.py tests/test_opencode_workflow_shell_syntax.py -q -> 30 passed, 2 skipped.
• git diff --check passed.
• CodeGraph synced and status OK: 71 files, 1,359 nodes, 3,359 edges.

Local limitation

• Direct Bash script execution is not usable on this Windows host because bash resolves to C:\WINDOWS\system32\bash.exe and times out. Python workflow-shell syntax/contract tests were run instead.

[seonghobae]

CodeGraph 초기화/동기화 후 변경 경로를 검증했습니다. 집중 계약 테스트 26개 통과, Trivy Medium/High/Critical 및 secret 0입니다. 전체 opencode-review workflow actionlint는 로컬에서 진단 없이 장시간 실행되어 중단했으며, current-head CI actionlint를 권위 있는 결과로 추적합니다. 정확한 HEAD에 squash auto-merge를 설정했습니다.

[opencode-agent]

Pull request overview

OpenCode model providers were unavailable for this same-head run, but deterministic current-head evidence is clean: coverage evidence passed, peer GitHub Checks are complete, medium-or-higher code-scanning alerts are clear, mergeability is clean, and reviewer threads are resolved or outdated.

Findings

No blocking findings.

Evidence

• Result: APPROVE
• Reason: current-head model-unavailable evidence fallback; coverage, docstring, peer GitHub Checks, code-scanning alerts, mergeability, and review threads were clear for current head.
• Scope: central OpenCode/Strix review-process
• Changed files: 2
• Model-pool outcome: exhausted
• Head SHA: 8afc47e0ecebc0077b5cde2698e8aec251ebe351
• Workflow run: 29204660458
• Workflow attempt: 1

This fallback does not suppress failed checks, medium-or-higher code-scanning alerts, merge conflicts, unresolved reviewer threads, or failed coverage evidence; any of those conditions still publish REQUEST_CHANGES or leave the approval state unchanged.