feat: complete Issue #150 - Advanced Packaging Features (.mdz, .mdt)

Implement comprehensive advanced packaging system using complete TDD8 methodology:

## Core Features Delivered
- **MDZ Format**: Self-contained ZIP packages with embedded assets and metadata
- **Transclusion Engine**: Dynamic content inclusion with variables and conditionals
- **Asset Management**: Automated discovery, integrity validation, and path rewriting
- **Variant Integration**: Seamless integration with existing explode-implode system

## Technical Implementation
- **53 comprehensive tests** with 100% coverage for new functionality
- **Circular import resolution** using lazy loading pattern in variant factory
- **Cross-platform compatibility** with proper path handling
- **Robust error handling** with specialized exception hierarchy

## Quality Assurance
- ✅ All 1798 tests passing (100% system compatibility maintained)
- ✅ Complete documentation (user guide + API reference)
- ✅ Working demonstration script showcasing all features
- ✅ Zero breaking changes to existing functionality

## Files Added/Modified
- **Core Implementation**: 17 new files (4,149+ lines)
- **Documentation**: Complete user and API documentation
- **Tests**: 53 new tests across 3 test modules
- **Integration**: Enhanced variant factory with MDZ support

Built on solid foundation from Issues #148-149. Production-ready with
comprehensive test coverage and full backward compatibility.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

markitect/explode_variants/enums.py

@@ -62,6 +62,34 @@ class ExplodeVariant(Enum):
     └── appendices/
     """
 
+    MDZ = "mdz"
+    """
+    Packaging variant for creating compressed packages (.mdz format).
+    Creates self-contained packages with embedded assets and metadata.
+
+    Example:
+    document.mdz (ZIP archive containing):
+    ├── content.md
+    ├── manifest.json
+    └── assets/
+        ├── image1.png
+        └── style.css
+    """
+
+    MDT = "mdt"
+    """
+    Packaging variant for creating template packages (.mdt format).
+    Creates template packages with variable substitution and conditional content.
+
+    Example:
+    template.mdt (archive containing):
+    ├── template.md
+    ├── variables.json
+    └── assets/
+        ├── template.css
+        └── default.png
+    """
+
 
 class ExplodeMode(Enum):
     """