docs(bin): give every bin skill a README

The bin skills were the only plugin without per-skill READMEs, so a reader
had to open SKILL.md — an agent-facing contract, not an explainer — to learn
what a skill does and when it fires. Each README states purpose, triggers and
boundaries for a human audience, leaving SKILL.md free to stay terse.

plugins/bin/.apm/skills/triage/README.md

@@ -0,0 +1,35 @@
+# triage
+
+Move issues on the project issue tracker through a small state machine of triage roles.
+
+## What it does
+
+Gives issue triage an explicit state model and a fixed set of moves. Every issue carries exactly one **category** role (`bug`, `enhancement`) and one **state** role (`needs-triage`, `needs-info`, `ready-for-agent`, `ready-for-human`, `wontfix`); conflicting state roles are flagged to the maintainer before anything else happens. Unlabeled issues normally enter at `needs-triage`; `needs-info` returns there once the reporter replies. The maintainer can override at any point, and unusual transitions are questioned rather than executed silently.
+
+A run does one of three things depending on what the maintainer asks for:
+
+- **Show what needs attention** — three buckets, oldest first: unlabeled, `needs-triage`, and `needs-info` with reporter activity since the last triage notes.
+- **Triage a specific issue** — gather context (including prior triage notes, so resolved questions are not re-asked, and `.out-of-scope/` records that resemble the issue), recommend a category and state with reasoning, attempt reproduction for bugs *before* any grilling, run a `grill-with-docs` session if the issue needs fleshing out, then apply the outcome.
+- **Quick state override** — "move #42 to ready-for-agent" is trusted and applied directly, skipping grilling, after confirming the exact changes.
+
+Two hard rules: every comment or issue the skill posts during triage must open with the AI-generated disclaimer, and the canonical role names above are *not* necessarily the label strings in the tracker — the mapping has to be supplied to the run.
+
+## Composition
+
+`grill-with-docs` is invoked at step 4 when an issue needs fleshing out; whatever that session establishes is carried into the triage notes so the work is not lost. The reverse direction also exists: `diagnose` names this skill as the place to send a *reported* bug that needs filing rather than debugging.
+
+## Usage
+
+```text
+/triage
+```
+
+Then describe what you want in natural language — "show me anything that needs my attention", "let's look at #42", "move #42 to ready-for-agent", "what's ready for agents to pick up?".
+
+## Files
+
+| File | Purpose |
+|------|---------|
+| `SKILL.md` | The roles and state machine, the three invocation modes, the needs-info template, and how to resume a prior session |
+| `AGENT-BRIEF.md` | Skill-root document, cited when an issue moves to `ready-for-agent` (and reused for `ready-for-human`): how to write a brief that stays durable for weeks while the codebase moves under it — describe interfaces and behavioural contracts, not line numbers |
+| `OUT-OF-SCOPE.md` | Skill-root document, cited when an enhancement is closed `wontfix` and when checking for prior rejections: how the `.out-of-scope/` knowledge base is laid out and what it is for — institutional memory, and deduplication against re-litigated requests |