feat: add Grok Build CLI provider

[canderson26]

Summary

Adds a first-class grok-build provider backed by the local Grok CLI.

• Registers grok-build in the provider registry, model catalog, aliases, model picker, runtime resolver, and auxiliary client path
• Adds GrokCliClient, an OpenAI-compatible shim around grok --prompt-file
• Defaults to --no-memory --disable-web-search --max-turns 1 --output-format plain --effort xhigh
• Supports HERMES_GROK_BUILD_COMMAND, GROK_CLI_PATH, HERMES_GROK_BUILD_ARGS, and HERMES_GROK_BUILD_EFFORT
• Documents setup and supported provider lists

Testing

• venv/bin/python -m py_compile agent/grok_cli_client.py hermes_cli/auth.py hermes_cli/models.py hermes_cli/runtime_provider.py hermes_cli/providers.py hermes_cli/model_normalize.py hermes_cli/main.py hermes_cli/model_switch.py hermes_cli/setup.py agent/auxiliary_client.py agent/model_metadata.py run_agent.py tests/agent/test_grok_cli_client.py tests/hermes_cli/test_api_key_providers.py tests/hermes_cli/test_model_validation.py tests/run_agent/test_run_agent.py
• venv/bin/python -m pytest tests/agent/test_grok_cli_client.py tests/hermes_cli/test_api_key_providers.py tests/hermes_cli/test_model_validation.py tests/run_agent/test_run_agent.py::test_aiagent_uses_grok_cli_client
• venv/bin/hermes chat -q "Reply exactly with: HERMES_GROK_BUILD_OK_2" --provider grok-build -m grok-build --ignore-rules

Notes

The provider relies on an already-authenticated local Grok CLI session. Run grok login and confirm grok models includes grok-build.

[alt-glitch]

Related xAI/Grok provider work:

• feat(providers): add first-class xAI (Grok) OAuth provider with Grok CLI auto-import #25968 — feat(providers): first-class xAI (Grok) OAuth provider with Grok CLI auto-import (open, P3)
• feat(providers): add xAI Coding Plan OAuth provider via grok CLI delegation #25941 — xAI Coding Plan OAuth via grok CLI delegation (open)

This PR adds a grok-build CLI-shim provider, which overlaps with #25968's approach of wrapping the Grok CLI. Please coordinate to avoid duplicated effort.

[canderson26]

Closing this polluted branch. It accidentally picked up unrelated local work after the Grok Build provider commit. A clean replacement branch/PR will be used instead.