Add new skills for TDD, issue management, PRD creation, and productivity tools

- Introduced TDD skills including deep modules, interface design, mocking, refactoring, and testing guidelines.
- Added skills for breaking plans into GitHub issues and creating PRDs from conversation context.
- Implemented productivity skills for scaffolding exercises, setting up pre-commit hooks, and managing notes in Obsidian.
- Created a caveman communication mode for concise technical responses and a grilling technique for thorough plan discussions.
- Developed a skill for writing new agent skills with structured templates and guidelines.
- Included git guardrails to prevent dangerous git commands and a migration guide for using @total-typescript/shoehorn in tests.

.claude-plugin/plugin.json

@@ -1,6 +1,20 @@
 {
   "name": "mattpocock-skills",
   "skills": [
-    "./skills/deprecated/design-an-interface"
+    "./skills/engineering/diagnose",
+    "./skills/engineering/domain-model",
+    "./skills/engineering/github-triage",
+    "./skills/engineering/improve-codebase-architecture",
+    "./skills/engineering/tdd",
+    "./skills/engineering/to-issues",
+    "./skills/engineering/to-prd",
+    "./skills/engineering/zoom-out",
+    "./skills/productivity/caveman",
+    "./skills/productivity/grill-me",
+    "./skills/productivity/write-a-skill",
+    "./skills/misc/git-guardrails-claude-code",
+    "./skills/misc/migrate-to-shoehorn",
+    "./skills/misc/scaffold-exercises",
+    "./skills/misc/setup-pre-commit"
   ]
 }