Summary

• add /side <question> as a side-question command in CLI and gateway
• let /side bypass the active-session guard so it can run without interrupting the main task
• add gateway regression tests for registration, bypass behavior, and session-race handling

Behavior

• uses current session context
• does not interrupt the active task
• runs with no tools
• does not persist side-question history into the main session

Test Plan

• python -m pytest tests/gateway/test_side_command.py tests/gateway/test_command_bypass_active_session.py tests/gateway/test_session_race_guard.py tests/hermes_cli/test_commands.py -q
• python -m py_compile cli.py gateway/run.py gateway/platforms/base.py hermes_cli/commands.py tests/gateway/test_side_command.py tests/gateway/test_command_bypass_active_session.py tests/gateway/test_session_race_guard.py

Notes

• reviewed the branch diff and cleaned the branch base so this PR contains only the /side feature commit