feat(hermes_governance): opt-in skill-budget governance plugin

[rinadelph]

Summary

Adds an opt-in hermes_governance plugin that ports a "Hermes-style" governance loop into Code Puppy: a skill-budget gate on tool calls, nudges that steer the agent toward creating/reusing skills, and background curation of stale agent-created skills. Implemented entirely through callback hooks — no core files are modified.

Opinionated by design / disabled by default. Enforcement is fully opt-in and a no-op unless explicitly armed. Opening as a draft for discussion on whether this belongs in core vs. as an external plugin.

What's included

code_puppy/plugins/hermes_governance/:

• enforcer.py — pre_tool_call/post_tool_call gate that enforces a skill budget and emits nudges.
• budget.py — the budget primitive (onboarding budget → expanded budget after first skill use).
• carrier.py / carrier_processor.py — state rides in the conversation via wrap_pydantic_agent; reset per run on agent_run_start.
• curator.py — session_end background curation that archives stale agent-created skills.
• nudges.py — system-reminder injection on user_prompt_submit.
• skill_manage.py — registers a skill_manage tool for on-demand skill lifecycle ops.
• config.py — configuration surface (see below).

Control surface

No standalone slash command. Governance is controlled entirely through puppy.cfg keys (auto-exposed in /set tab-completion):

/set hermes_governance_enabled=true          # arm the gate + nudges
/set hermes_governance_enabled=false         # disarm (default)
/set hermes_governance_onboarding_budget=5
/set hermes_governance_max_budget=90

Design

• Plugin-only; no edits to core. All hooks fail gracefully and are no-ops while disarmed.
• Every referenced hook (pre_tool_call, post_tool_call, wrap_pydantic_agent, agent_run_start, session_end, user_prompt_submit, register_tools) is part of the documented callback surface.

Testing

• ruff check / ruff format clean.
• All files under the project's 600-line cap.

Risk

Low when disabled (default). When enabled, it intentionally gates tool calls — that's the feature. Happy to adjust scope/behaviour based on review.