Add Hermes Agent plugin

## Summary Adds a minimal Hermes Agent adapter for Ponytail. The adapter reuses the existing `skills/` content and exposes Ponytail to Hermes as an explicit opt-in plugin. Hermes starts with Ponytail OFF by default. Users can turn it ON with `/ponytail on`, `/ponytail lite`, `/ponytail full`, or `/ponytail ultra`, and turn it off with `/ponytail off`. The reason it's off by default is due to some users not always using their Hermes Agents for coding, so it would be wrong to have this plugin always enabled. It's also tricky to know when is the right time to automatically enable it, so users can exercise discretion and ask their agent to enable/disable the plugin automatically if they don't want to explicitly turn it on/off. ## Hermes Behavior ```bash hermes plugins install DietrichGebert/ponytail --enable ``` After restart, Hermes loads the plugin but does not inject Ponytail until the user explicitly turns it on: - `/ponytail on` --> defaults to `full` mode - `/ponytail full` - `/ponytail lite` - `/ponytail ultra` - `/ponytail off` --> off When active, the plugin injects the selected Ponytail ruleset through Hermes' `pre_llm_call` hook. ## Validation - Python smoke test for Hermes adapter registration and strict on/off behavior - `node scripts/check-rule-copies.js` - `PATH="$PWD/.venv/bin:$PATH" npm test` - Ponytail tests: 36 passed - Pi extension tests: 11 passed - Installed locally with `hermes plugins install file://... --enable --force` - Verified Hermes plugin discovery, command registration, skill registration, default-off behavior, strict slash-command mode injection, and no natural-language shutdown handling - Ran it on this PR