Add agent-skills config for Gitea + triage

Scaffolds the per-repo config the mattpocock engineering skills expect:
- AGENTS.md with the ## Agent skills block (issue tracker, triage labels, domain docs)
- docs/agents/issue-tracker.md — Gitea REST API workflow (gh/glab don't apply)
- docs/agents/triage-labels.md — canonical role -> Gitea label mapping (1:1)
- docs/agents/domain.md — single-context CONTEXT.md/ADR consumer rules

Triage state labels (needs-triage, needs-info, ready-for-agent, ready-for-human,
wontfix) created in the tracker; all open issues seeded with needs-triage.
Run triage with /mattpocock-skills:triage.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DgbgipE41xwPcQJnhnq1J1

AGENTS.md

@@ -0,0 +1,22 @@
+# AGENTS.md
+
+Guidance for AI agents working in this repo.
+
+## Agent skills
+
+### Issue tracker
+
+Issues live in **Gitea** at <https://git.mivanchenko.de/BPPP/smb-online/issues>, created/read via
+the Gitea REST API (or the `tea` CLI) with a PAT that has `issue` scope, kept in `.secrets/` and
+never committed. See `docs/agents/issue-tracker.md`.
+
+### Triage labels
+
+Canonical roles, used verbatim as Gitea labels: categories `bug` / `enhancement`; states
+`needs-triage` · `needs-info` · `ready-for-agent` · `ready-for-human` · `wontfix`. Invoke triage
+with `/mattpocock-skills:triage`. See `docs/agents/triage-labels.md`.
+
+### Domain docs
+
+Single-context: one `CONTEXT.md` + `docs/adr/` at the repo root (created lazily when terms or
+decisions get resolved). See `docs/agents/domain.md`.