docs(agents): add pr-review and triage-prs skills, always-on communication guidance
- pr-review: maintainer-proxy verdict review (decline / push-back /
merge-then-fix / merge) with ready-to-post actions, product-fit
escalation, ache salvage on declines, and merge-base diff measurement
- triage-prs: batch queue triage pipeline (mechanical sweep, duplicate
clusters, fan-out verdict reviews, approved batch actions) with
canonical message templates
- AGENTS.md: new Communication section replaces the always-load
communication-style mandate; the skill keeps a trigger-based
description for editing human-facing text
- register all project skills in .claude/skills (only 6 of 17 were
linked, leaving most skills undiscoverable)