fix(cli): honor skills in oneshot mode

[Nigelkil01]

Summary

• Thread top-level and Termux fast-path --skills through to oneshot mode
• Preload requested skills with the same skill prompt builder used by chat mode
• Fail loudly when oneshot receives an unknown skill instead of silently ignoring it

Test Plan

• pytest tests/hermes_cli/test_tui_resume_flow.py::test_termux_fast_cli_launch_oneshot_uses_light_parser tests/hermes_cli/test_tui_resume_flow.py::test_main_top_level_oneshot_accepts_toolsets tests/hermes_cli/test_tui_resume_flow.py::test_main_top_level_oneshot_accepts_skills tests/hermes_cli/test_tui_resume_flow.py::test_oneshot_preloads_skills_into_ephemeral_system_prompt -o addopts='' -q
• pytest tests/hermes_cli/test_tui_resume_flow.py -o addopts='' -q
• python -m py_compile hermes_cli/oneshot.py hermes_cli/main.py tests/hermes_cli/test_tui_resume_flow.py
• git diff --check

Fixes #31548

[alt-glitch]

Duplicate of #31591 — both fix #31548 (oneshot mode silently drops --skills flag). Same files changed, same fix approach.

[Nigelkil01]

Thanks for catching that — I missed the existing PR during triage. Closing this as a duplicate to avoid wasting maintainer time.