Add writing-for-agents skill documentation and related files

- Created SKILL.md and SKILL-MECHANICS.md for writing agent skills.
- Added openai.yaml for agent interface configuration.
- Introduced AGENTS.md for agent skills overview.
- Established CONTEXT.md for personal leave planning terminology.
- Documented ordered heuristic optimization in ADRs.
- Defined personal client-side planner limitations in ADRs.
- Created domain documentation for engineering skills.
- Added issue tracker guidelines for GitLab.
- Mapped triage labels for issue tracking.
- Initialized skills-lock.json to manage skill dependencies.

.agents/skills/grill-me/agents/openai.yaml

@@ -0,0 +1,5 @@
+interface:
+  display_name: "Grill Me"
+  short_description: "Sharpen a plan through interview"
+policy:
+  allow_implicit_invocation: false