Add setup-matt-pocock-skills; rename github-triage to triage; migrate engineering skills to vague prose

Engineering skills no longer hard-code GitHub or specific label strings.
A new setup skill scaffolds an `## Agent skills` block in
AGENTS.md/CLAUDE.md plus `docs/agents/` so each repo can declare its own
backlog backend, triage label vocabulary, and domain doc layout. Skills
that need the mapping (to-issues, to-prd, triage) point at the setup
skill; skills that only soften with it (diagnose, tdd,
improve-codebase-architecture, zoom-out) stay vague. ADR-0001 records
the split.

Closes #88, #89.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

skills/engineering/setup-matt-pocock-skills/triage-labels.md

@@ -0,0 +1,15 @@
+# Triage Labels
+
+The skills speak in terms of five canonical triage roles. This file maps those roles to the actual label strings used in this repo's backlog.
+
+| Label in mattpocock/skills | Label in our backlog | Meaning                                  |
+| -------------------------- | -------------------- | ---------------------------------------- |
+| `needs-triage`             | `needs-triage`       | Maintainer needs to evaluate this issue  |
+| `needs-info`               | `needs-info`         | Waiting on reporter for more information |
+| `ready-for-agent`          | `ready-for-agent`    | Fully specified, ready for an AFK agent  |
+| `ready-for-human`          | `ready-for-human`    | Requires human implementation            |
+| `wontfix`                  | `wontfix`            | Will not be actioned                     |
+
+When a skill mentions a role (e.g. "apply the AFK-ready triage label"), use the corresponding label string from this table.
+
+Edit the right-hand column to match whatever vocabulary you actually use.