[codex] add Grok Build capability probe

[vansin]

Author & Helpers

Author-Agent: 通信SDK牛
Helpers: 通信牛 (dispatch + research), Vincent (request)

Summary

• Add Docker-based Grok Build capability probe suite.
• Generate docs/tests/report-grok-build-capability.md with PASS/FAIL/SKIP/WARN results and verdict.
• Document how to run the probe with GROK_CODE_XAI_API_KEY.

Validation

• bash -n tests/test-grok-build-capability/run.sh
• sg docker -c 'docker build -t agent-network-grok-probe -f tests/test-grok-build-capability/Dockerfile .'
• sg docker -c 'docker run --rm -v "$PWD/docs/tests:/work/docs/tests" agent-network-grok-probe'

Current Probe Result

• Docker installed Grok Build inside the container and reported grok 0.1.211 (2f2cd6d5c).
• GROK_CODE_XAI_API_KEY was not available in this environment, so authenticated checks are skipped and verdict remains Wait.
• Phase 1 runtime implementation is intentionally not included until capability probe passes.

Refs #164