Deep codebase initialization with hierarchical AGENTS.md documentation

# Deep Init Skill

Creates comprehensive, hierarchical AGENTS.md documentation across the entire codebase.

## Core Concept

AGENTS.md files serve as **AI-readable documentation** that helps agents understand:
- What each directory contains
- How components relate to each other
- Special instructions for working in that area
- Dependencies and relationships

## Hierarchical Tagging System

Every AGENTS.md (except root) includes a parent reference tag:

```markdown
<!-- Parent: ../AGENTS.md -->
```

This creates a navigable hierarchy:
```
/AGENTS.md                          ← Root (no parent tag)
├── src/AGENTS.md                   ← <!-- Parent: ../AGENTS.md -->
│   ├── src/components/AGENTS.md    ← <!-- Parent: ../AGENTS.md -->