fix(hermes): turn ponytail off when the user types "stop ponytail" (#1167)

[szsunyuan]

Summary

• The Hermes plugin ignored a typed "stop ponytail" or "normal mode". Its mode stayed on, bare /ponytail still reported the level, and after compaction _pre_llm_call re-injected the ruleset, so ponytail came back on by itself.
• _pre_llm_call now reads user_message and applies the same standalone rule as isDeactivationCommand (hooks/ponytail-config.js). It switches the mode off, so the off notice from fix(hermes): send the off notice after /ponytail off (#1121) #1122 goes out once and compaction no longer brings the ruleset back.
• In a gateway the mode is process-wide and Hermes never slash-gates plain chat. So rewrite_gateway_command rewrites the phrase to /ponytail off, which then passes the same access control as the command. INSTALL.md says so in one clause.

Closes #1167

Out of scope

• Per-chat modes in a shared gateway: the mode stays process-wide, as /ponytail off already is.
• Other adapters.

Test plan

• node scripts/check-rule-copies.js
• node scripts/check-versions.js
• git diff --check
• npm test: 145/145 root, 30/30 pi-extension
• New test Hermes treats a typed "stop ponytail" like /ponytail off, and a gateway runs it as that command is red on upstream/main (null instead of { context: 'PONYTAIL MODE OFF' })
• The Python rule gives the same answer as isDeactivationCommand on 14 phrases (case, trailing punctuation, extra words)
• Not run in a live Hermes session. I read the gateway path in Hermes 32b77f51: a pre_gateway_dispatch rewrite replaces event.text, and plugin commands then go through _check_slash_access like built-ins.