fix(cli): Fix oneshot skills preload

[GarlicGo]

Summary

• pass top-level --skills through both oneshot launch paths
• preload requested skills into the oneshot agent system prompt
• add regression coverage for CLI forwarding and oneshot skill prompt injection

Root cause

hermes -z/--oneshot accepted --skills at the parser layer, but the oneshot launch path did not pass that value into run_oneshot(), and the oneshot agent construction did not build the preloaded skill prompt.

Fixes #31548.

Tests

• uv run --with pytest --with pytest-timeout python -m pytest tests/hermes_cli/test_tui_resume_flow.py -q
• git diff --check

[teknium1]

Thanks for targeting a real current-main gap: both -z/--oneshot dispatches still drop args.skills (hermes_cli/main.py:12580-12586, hermes_cli/main.py:14737-14743), and hermes_cli/oneshot.py:169-426 has no skill-prompt path.

Problems

• The proposed helper fails whenever any skill is missing. That differs from the existing CLI contract: cli.py:15931-15947 continues when at least one requested skill loaded, and fails only when all are missing.
• This branch conflicts with current main, whose oneshot path now includes usage_file and uses _run_agent() → run_conversation() returning (response, result) (hermes_cli/oneshot.py:425-426). The added fake agent's chat() method no longer matches that current contract.

Suggested changes

• Preserve current usage_file forwarding, add the two skills forwards, and inject the built payload through ephemeral_system_prompt.
• Mirror the mixed-valid/missing behavior in cli.py:15931-15947; add regression coverage for that case and for the current run_conversation() return shape.

Automated hermes-sweeper review.

[teknium1]

Merged via PR #90389 — your commits were cherry-picked onto current main with your authorship preserved in git log, plus a widening fix for a fast-path call site added after your PR. Thanks for the fix, and for being the earliest of five independent submissions!