chore(agents): install mattpocock skills + per-repo agent config

- 38 skills from mattpocock/skills into .agents/skills/ (symlinked into
  .claude/skills/ for Claude Code)
- skills-lock.json for reproducible installs
- docs/agents/: issue-tracker (Gitea via tea CLI), triage-labels
  (default five-role vocabulary), domain docs (single-context)
- CLAUDE.md: add '## Agent skills' section pointing at docs/agents/
- .gitignore: un-ignore docs/agents/ under the local /docs/* rule

.agents/skills/implement-spec/SKILL.md

@@ -0,0 +1,35 @@
+---
+name: implement-spec
+description: "Implement a specification in code."
+disable-model-invocation: true
+---
+
+You have been provided a spec. This spec should have tickets associated with it, describing how to implement the spec.
+
+The goal is a PR which implements the entire spec on a single branch.
+
+The tickets are not a list of steps. They are a **task graph** with blocking relationships between them. This means there is always a **frontier** of tickets which are ready to be grabbed.
+
+Communication to and from subagents should be sparse. Communicate primarily through **context pointers**: to the spec, tickets, research notes, and previous commits. Don't duplicate information already available via pointers.
+
+**Implementer subagents** should be run in the background where possible for **maximum concurrency**.
+
+## Steps
+
+1. Read the spec and tickets. Read enough to understand the task graph.
+
+2. (optional) Use an **exploration subagent** to conduct any exploration required by the tickets - relevant codebase files or external documentation. Ensure the exploration subagent can save files - it should save its markdown notes in a directory outside the repo, accessible by all future subagents. This lets **implementer subagents** focus on implementation rather than exploration.
+
+3. Create a branch, and a draft PR. The PR should be marked as 'closing' the spec issue and tickets.
+
+4. Use **implementer subagents** to implement each ticket. Each implementer subagent should work in its own worktree, on its own branch.
+
+5. Once an **implementer subagent** completes, merge its work to the PR branch with a **merger subagent**.
+
+6. If this changes the **frontier** of available tickets, kick off more **implementer subagents** to work on the new tickets. This allows for maximum concurrency.
+
+7. Once all tickets are complete, run /code-review on the PR branch. Fix all issues raised by the code review in a single **implementer subagent**.
+
+8. Mark the PR as ready for review.
+
+9. Clean up all **implementer subagent** worktrees.

.agents/skills/implement-spec/agents/openai.yaml

@@ -0,0 +1,5 @@
+interface:
+  display_name: "Implement Spec"
+  short_description: "Implement a whole spec as one PR"
+policy:
+  allow_implicit_invocation: false