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/productivity/README.md

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+# Productivity
+
+General workflow tools, not code-specific.

skills/productivity/caveman/SKILL.md

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+---
+name: caveman
+description: >
+  Ultra-compressed communication mode. Cuts token usage ~75% by dropping
+  filler, articles, and pleasantries while keeping full technical accuracy.
+  Use when user says "caveman mode", "talk like caveman", "use caveman",
+  "less tokens", "be brief", or invokes /caveman.
+---
+
+Respond terse like smart caveman. All technical substance stay. Only fluff die.
+
+## Persistence
+
+ACTIVE EVERY RESPONSE once triggered. No revert after many turns. No filler drift. Still active if unsure. Off only when user says "stop caveman" or "normal mode".
+
+## Rules
+
+Drop: articles (a/an/the), filler (just/really/basically/actually/simply), pleasantries (sure/certainly/of course/happy to), hedging. Fragments OK. Short synonyms (big not extensive, fix not "implement a solution for"). Abbreviate common terms (DB/auth/config/req/res/fn/impl). Strip conjunctions. Use arrows for causality (X -> Y). One word when one word enough.
+
+Technical terms stay exact. Code blocks unchanged. Errors quoted exact.
+
+Pattern: `[thing] [action] [reason]. [next step].`
+
+Not: "Sure! I'd be happy to help you with that. The issue you're experiencing is likely caused by..."
+Yes: "Bug in auth middleware. Token expiry check use `<` not `<=`. Fix:"
+
+### Examples
+
+**"Why React component re-render?"**
+
+> Inline obj prop -> new ref -> re-render. `useMemo`.
+
+**"Explain database connection pooling."**
+
+> Pool = reuse DB conn. Skip handshake -> fast under load.
+
+## Auto-Clarity Exception
+
+Drop caveman temporarily for: security warnings, irreversible action confirmations, multi-step sequences where fragment order risks misread, user asks to clarify or repeats question. Resume caveman after clear part done.
+
+Example -- destructive op:
+
+> **Warning:** This will permanently delete all rows in the `users` table and cannot be undone.
+>
+> ```sql
+> DROP TABLE users;
+> ```
+>
+> Caveman resume. Verify backup exist first.

skills/productivity/grill-me/SKILL.md

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+---
+name: grill-me
+description: Interview the user relentlessly about a plan or design until reaching shared understanding, resolving each branch of the decision tree. Use when user wants to stress-test a plan, get grilled on their design, or mentions "grill me".
+---
+
+Interview me relentlessly about every aspect of this plan until we reach a shared understanding. Walk down each branch of the design tree, resolving dependencies between decisions one-by-one. For each question, provide your recommended answer.
+
+Ask the questions one at a time.
+
+If a question can be answered by exploring the codebase, explore the codebase instead.

skills/productivity/write-a-skill/SKILL.md

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+---
+name: write-a-skill
+description: Create new agent skills with proper structure, progressive disclosure, and bundled resources. Use when user wants to create, write, or build a new skill.
+---
+
+# Writing Skills
+
+## Process
+
+1. **Gather requirements** - ask user about:
+   - What task/domain does the skill cover?
+   - What specific use cases should it handle?
+   - Does it need executable scripts or just instructions?
+   - Any reference materials to include?
+
+2. **Draft the skill** - create:
+   - SKILL.md with concise instructions
+   - Additional reference files if content exceeds 500 lines
+   - Utility scripts if deterministic operations needed
+
+3. **Review with user** - present draft and ask:
+   - Does this cover your use cases?
+   - Anything missing or unclear?
+   - Should any section be more/less detailed?
+
+## Skill Structure
+
+```
+skill-name/
+├── SKILL.md           # Main instructions (required)
+├── REFERENCE.md       # Detailed docs (if needed)
+├── EXAMPLES.md        # Usage examples (if needed)
+└── scripts/           # Utility scripts (if needed)
+    └── helper.js
+```
+
+## SKILL.md Template
+
+```md
+---
+name: skill-name
+description: Brief description of capability. Use when [specific triggers].
+---
+
+# Skill Name
+
+## Quick start
+
+[Minimal working example]
+
+## Workflows
+
+[Step-by-step processes with checklists for complex tasks]
+
+## Advanced features
+
+[Link to separate files: See [REFERENCE.md](REFERENCE.md)]
+```
+
+## Description Requirements
+
+The description is **the only thing your agent sees** when deciding which skill to load. It's surfaced in the system prompt alongside all other installed skills. Your agent reads these descriptions and picks the relevant skill based on the user's request.
+
+**Goal**: Give your agent just enough info to know:
+
+1. What capability this skill provides
+2. When/why to trigger it (specific keywords, contexts, file types)
+
+**Format**:
+
+- Max 1024 chars
+- Write in third person
+- First sentence: what it does
+- Second sentence: "Use when [specific triggers]"
+
+**Good example**:
+
+```
+Extract text and tables from PDF files, fill forms, merge documents. Use when working with PDF files or when user mentions PDFs, forms, or document extraction.
+```
+
+**Bad example**:
+
+```
+Helps with documents.
+```
+
+The bad example gives your agent no way to distinguish this from other document skills.
+
+## When to Add Scripts
+
+Add utility scripts when:
+
+- Operation is deterministic (validation, formatting)
+- Same code would be generated repeatedly
+- Errors need explicit handling
+
+Scripts save tokens and improve reliability vs generated code.
+
+## When to Split Files
+
+Split into separate files when:
+
+- SKILL.md exceeds 100 lines
+- Content has distinct domains (finance vs sales schemas)
+- Advanced features are rarely needed
+
+## Review Checklist
+
+After drafting, verify:
+
+- [ ] Description includes triggers ("Use when...")
+- [ ] SKILL.md under 100 lines
+- [ ] No time-sensitive info
+- [ ] Consistent terminology
+- [ ] Concrete examples included
+- [ ] References one level deep