Two related changes to the skill curator:
1. Built-in pruning. New curator.prune_builtins config (default on) lets the
curator archive bundled built-in skills after the inactivity period, not
just agent-created ones. A .curator_suppressed list tells the update-time
re-seeder (tools/skills_sync) to leave pruned built-ins archived, so the
prune is durable across `hermes update`. Built-ins are seeded with a
baseline record on first sight, so the inactivity clock starts at upgrade
time -- no mass-prune on the first run. Hub-installed skills are never
pruned regardless of the flag. Restoring a built-in clears its suppression.
2. Usage tracking for all skills. Telemetry (view/use/patch) was wrongly gated
behind curation-eligibility, so built-ins were tracked only when prunable
and hub skills never. Telemetry is observability and is now decoupled from
curation: every skill accrues usage counts regardless of provenance, while
lifecycle mutators (set_state/set_pinned/mark_agent_created) stay
curation-gated. New usage_report() + provenance() expose all skills with an
agent/bundled/hub tag.