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.

skills/engineering/to-issues/SKILL.md

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+---
+name: to-issues
+description: Break a plan, spec, or PRD into independently-grabbable GitHub issues using tracer-bullet vertical slices. Use when user wants to convert a plan into issues, create implementation tickets, or break down work into issues.
+---
+
+# To Issues
+
+Break a plan into independently-grabbable GitHub issues using vertical slices (tracer bullets).
+
+## Process
+
+### 1. Gather context
+
+Work from whatever is already in the conversation context. If the user passes a GitHub issue number or URL as an argument, fetch it with `gh issue view <number>` (with comments).
+
+### 2. Explore the codebase (optional)
+
+If you have not already explored the codebase, do so to understand the current state of the code.
+
+### 3. Draft vertical slices
+
+Break the plan into **tracer bullet** issues. Each issue is a thin vertical slice that cuts through ALL integration layers end-to-end, NOT a horizontal slice of one layer.
+
+Slices may be 'HITL' or 'AFK'. HITL slices require human interaction, such as an architectural decision or a design review. AFK slices can be implemented and merged without human interaction. Prefer AFK over HITL where possible.
+
+<vertical-slice-rules>
+- Each slice delivers a narrow but COMPLETE path through every layer (schema, API, UI, tests)
+- A completed slice is demoable or verifiable on its own
+- Prefer many thin slices over few thick ones
+</vertical-slice-rules>
+
+### 4. Quiz the user
+
+Present the proposed breakdown as a numbered list. For each slice, show:
+
+- **Title**: short descriptive name
+- **Type**: HITL / AFK
+- **Blocked by**: which other slices (if any) must complete first
+- **User stories covered**: which user stories this addresses (if the source material has them)
+
+Ask the user:
+
+- Does the granularity feel right? (too coarse / too fine)
+- Are the dependency relationships correct?
+- Should any slices be merged or split further?
+- Are the correct slices marked as HITL and AFK?
+
+Iterate until the user approves the breakdown.
+
+### 5. Create the GitHub issues
+
+For each approved slice, create a GitHub issue using `gh issue create`. Use the issue body template below.
+
+Create issues in dependency order (blockers first) so you can reference real issue numbers in the "Blocked by" field.
+
+<issue-template>
+## Parent
+
+#<parent-issue-number> (if the source was a GitHub issue, otherwise omit this section)
+
+## What to build
+
+A concise description of this vertical slice. Describe the end-to-end behavior, not layer-by-layer implementation.
+
+## Acceptance criteria
+
+- [ ] Criterion 1
+- [ ] Criterion 2
+- [ ] Criterion 3
+
+## Blocked by
+
+- Blocked by #<issue-number> (if any)
+
+Or "None - can start immediately" if no blockers.
+
+</issue-template>
+
+Do NOT close or modify any parent issue.