hermes - 💡(How to fix) Fix [Feature]: Per-skill opt-out flag for background skill review

Problem or Use Case

bg-review (agent/background_review.py) fires automatically after qualifying turns and writes to skill files via skill_manage. The only way to disable it is global — skills.creation_nudge_interval: 0 in ~/.hermes/config.yaml, loaded at agent/agent_init.py:1042-1045. There is no way to mark a single skill as exempt.

Concrete case: a daily-briefing cron run authored two near-duplicate reference files (daily-briefing-cron.md + daily-briefing-pattern.md) in 9 seconds during one bg-review pass post-cron (08:03:51 and 08:04:00 in agent.log). For skills that maintain hand-curated or generator-managed references, having bg-review rewrite them is destructive — but turning it off globally also disables it for skills that genuinely benefit.

Proposed Solution

Honor a frontmatter flag in SKILL.md:

---
name: hermes-agent
auto_review: false   # opt out of bg-review for this skill
---

At agent/background_review.py (the skill review path), read the flag for skills referenced in the conversation and skip them in skill_manage patch/write calls. The flag affects only bg-review; users can still patch the skill manually.

Alternatives Considered

• Reuse the existing pinned flag — but pin currently blocks only deletion (tools/skill_manager_tool.py:142-156 explicitly: "Patches and edits are allowed on pinned skills; only deletion is blocked"). Expanding pin semantics would be more disruptive than adding a new flag.
• Raising creation_nudge_interval globally — reduces frequency but does not give per-skill control.

Feature Type: Configuration option Scope: Small