chore(agents): point Matt Pocock skills at the beads issue tracker

The engineering skills (to-tickets, triage, spec, wayfinder) need to know
where issues live for this repo. It is not the Gitea forge remote; it is
bd/beads, which AGENTS.md already mandates for all task tracking.

Adds docs/agents/issue-tracker.md (bd commands and wayfinding mapping),
docs/agents/triage-labels.md (five canonical roles kept as-is, applied
with bd tag / bd label add), docs/agents/domain.md (single-context
layout: CONTEXT.md plus docs/adr/ at the root), and an 'Agent skills'
index block in AGENTS.md. The pre-existing staged deletion of CLAUDE.md
is left out of this commit and stays in the index.

docs/agents/domain.md

@@ -0,0 +1,55 @@
+# Domain Docs
+
+How the engineering skills should consume this repo's domain documentation when exploring the codebase.
+
+## Before exploring, read these
+
+- **`CONTEXT.md`** at the repo root, or
+- **`CONTEXT-MAP.md`** at the repo root if it exists — it points at one `CONTEXT.md` per context. Read each one relevant to the topic.
+- **`docs/adr/`** — read ADRs that touch the area you're about to work in. In multi-context repos, also check `src/<context>/docs/adr/` for context-scoped decisions.
+
+If any of these files don't exist, **proceed silently**. Don't flag their absence; don't suggest creating them upfront. The `/domain-modeling` skill (reached via `/grill-with-docs` and `/improve-codebase-architecture`) creates them lazily when terms or decisions actually get resolved.
+
+## File structure
+
+Single-context repo (most repos):
+
+```
+/
+├── CONTEXT.md
+├── docs/adr/
+│   ├── 0001-two-overlay-strategies.md
+│   └── 0002-package-discovery-via-git-index.md
+├── packages/
+├── overlays/
+└── modules/
+```
+
+This repo uses the single-context layout. There is no `CONTEXT-MAP.md` and no per-directory `CONTEXT.md` files; the whole overlay is one domain.
+
+Multi-context repo (presence of `CONTEXT-MAP.md` at the root):
+
+```
+/
+├── CONTEXT-MAP.md
+├── docs/adr/                          ← system-wide decisions
+└── src/
+    ├── ordering/
+    │   ├── CONTEXT.md
+    │   └── docs/adr/                  ← context-specific decisions
+    └── billing/
+        ├── CONTEXT.md
+        └── docs/adr/
+```
+
+## Use the glossary's vocabulary
+
+When your output names a domain concept (in an issue title, a refactor proposal, a hypothesis, a test name), use the term as defined in `CONTEXT.md`. Don't drift to synonyms the glossary explicitly avoids.
+
+If the concept you need isn't in the glossary yet, that's a signal — either you're inventing language the project doesn't use (reconsider) or there's a real gap (note it for `/domain-modeling`).
+
+## Flag ADR conflicts
+
+If your output contradicts an existing ADR, surface it explicitly rather than silently overriding:
+
+> _Contradicts ADR-0007 (event-sourced orders) — but worth reopening because…_