Comprehensive documentation restructuring to improve discoverability,
organization, and progressive learning using incremental reveal methodology.

## Changes

### File Reorganization (17 files moved)
- Moved strategic docs to docs/strategic/ (vision, roadmap, critical-gaps)
- Moved SDK guides to docs/reference/ (sdk-development-guide, sdk-quick-reference, implementation-summary)
- Moved specifications to docs/specifications/ (main-spec, zkp-templates)
- Moved user guides to docs/user-guide/ (did-web-guide, selective-disclosure, transparency-log, profile-validators)
- Moved developer guides to docs/developer-guide/ (contributing, security)
- Moved core docs to docs/ (faq, use-cases, quickstart)

### New Bridge Documents (4 created)
- docs/getting-started/examples.md - Hands-on examples with progressive depth
- docs/user-guide/overview.md - User guide entry point with feature landscape
- docs/user-guide/disclosure-levels.md - Deep dive into A/B/C model (core innovation)
- DOCS_NAVIGATION.md - Comprehensive navigation guide with learning paths

### Enhanced Entry Points
- README.md: Restructured with 4-layer progressive learning paths
  - Layer 1: Essential basics (5-10 min)
  - Layer 2: User guidance (15-30 min)
  - Layer 3: Technical depth (30-60 min)
  - Layer 4: Strategic context (20-45 min)
- README.md: Added role-based quick navigation (developers, decision-makers, AI engineers, researchers)
- README.md: Updated all internal links to match new structure

### Navigation Improvements
- docs/index.md: Restructured cards to show 4 layers clearly
- docs/index.md: Fixed broken links to match reorganized structure
- mkdocs.yml: Updated navigation with layer-based organization
- mkdocs.yml: Added comments explaining incremental reveal structure

## Incremental Reveal Principles Applied

1. **Progressive Depth**: Documentation layered from simple → complex
2. **Clear Entry Points**: Multiple paths based on user role and goals
3. **Reduced Cognitive Load**: Each layer focuses on specific learning outcomes
4. **Signposting**: Clear "next steps" at each stage
5. **Role-Based Navigation**: Tailored paths for different audiences

## Benefits

- Easier onboarding for new users (clear 5-min → 10-min → 15-min paths)
- Better discoverability (organized by user journey, not document type)
- Aligned with MkDocs structure (documentation site ready)
- Reduced root directory clutter (16 files → organized structure)
- Improved navigation (role-based and layer-based access)

## Files Changed

- Renamed: 17 files moved to proper directories
- Created: 4 new bridge/navigation documents
- Modified: 3 files (README, docs/index, mkdocs.yml)
- Total: 24 files affected

## Migration Guide

All documentation remains accessible. Old paths redirect via git renames:
- QUICKSTART.md → docs/getting-started/quickstart.md
- FAQ.md → docs/faq.md
- ROADMAP.md → docs/strategic/roadmap.md
- (See DOCS_NAVIGATION.md for complete mapping)