docs: add domain glossary and agent skill configuration

- CONTEXT.md: domain glossary with 20+ terms, relationships, example
  dialogue, flagged ambiguities, and known issues from grill-with-docs
- docs/agents/: issue tracker (GitHub), triage labels (defaults), and
  domain doc layout (single-context) for engineering skills
- CLAUDE.md: append Agent skills section pointing to docs/agents/
- .gitignore: whitelist CONTEXT.md and docs/agents/*.md

docs/agents/issue-tracker.md

@@ -0,0 +1,22 @@
+# Issue tracker: GitHub
+
+Issues and PRDs for this repo live as GitHub issues. Use the `gh` CLI for all operations.
+
+## Conventions
+
+- **Create an issue**: `gh issue create --title "..." --body "..."`. Use a heredoc for multi-line bodies.
+- **Read an issue**: `gh issue view <number> --comments`, filtering comments by `jq` and also fetching labels.
+- **List issues**: `gh issue list --state open --json number,title,body,labels,comments --jq '[.[] | {number, title, body, labels: [.labels[].name], comments: [.comments[].body]}]'` with appropriate `--label` and `--state` filters.
+- **Comment on an issue**: `gh issue comment <number> --body "..."`
+- **Apply / remove labels**: `gh issue edit <number> --add-label "..."` / `--remove-label "..."`
+- **Close**: `gh issue close <number> --comment "..."`
+
+Infer the repo from `git remote -v` — `gh` does this automatically when run inside a clone.
+
+## When a skill says "publish to the issue tracker"
+
+Create a GitHub issue.
+
+## When a skill says "fetch the relevant ticket"
+
+Run `gh issue view <number> --comments`.