fix(acp): preload startup skills

[haran2001]

Summary

• Add ACP --skills/-s parsing and normalize repeated or comma-separated skill names.
• Pass startup skills into ACP session creation and inject loaded skill content through the agent's ephemeral system prompt.
• Forward top-level Hermes --skills values when launching ACP mode.

Test Plan

• python -m pytest tests/acp/test_entry.py tests/acp/test_session.py -q -o 'addopts='

Closes #24466

[alt-glitch]

Duplicate of #24474. Both pass --skills flag through to ACP sessions, fixing #24466. Four other competing PRs (#24521, #24526, #24635, #24683) have already been closed as duplicates of #24474.

[haran2001]

Closing as duplicate of #24474, which covers passing --skills through to ACP sessions for #24466.