feat: implement Issue #143 - CLI integration and user experience for asset management

Complete implementation of asset management CLI commands with comprehensive
user experience improvements:

## Core Features
- Asset management commands: add, list, stats, cleanup
- Package management commands: create, extract, list, validate
- Workspace management commands: init, status, sync

## CLI Integration
- Seamless integration with existing markitect CLI patterns
- Consistent Click command group registration
- Professional output formatting with checkmarks and structured details
- Comprehensive help text with examples and feature descriptions

## Code Quality
- Extracted common CLI utilities for consistent UX patterns
- Robust error handling with informative messages
- Configuration integration with sensible defaults
- Path validation and workspace management

## Testing & Quality Assurance
- Comprehensive integration tests covering all command groups
- No regressions in existing CLI functionality
- End-to-end workflow validation
- Production-ready error handling and edge cases

## Documentation
- Enhanced docstrings with usage examples
- Comprehensive --help text for all commands
- Clear argument descriptions and feature highlights

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

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

asset_registry.json

@@ -1,3 +1,20 @@
 {
-  "assets": {}
+  "assets": {
+    "ce929473e245c3323128ed7b84ab48a8553cdeea5275c702427d69fdff1db453": {
+      "path": "/home/worsch/markitect_project/assets/ce/ce929473e245c3323128ed7b84ab48a8553cdeea5275c702427d69fdff1db453.txt",
+      "content_hash": "ce929473e245c3323128ed7b84ab48a8553cdeea5275c702427d69fdff1db453",
+      "mime_type": "text/plain",
+      "size": 23,
+      "created_at": "2025-10-14T11:39:25.556553",
+      "description": "Test asset for validation"
+    },
+    "eb41ad8186ddebf801dd8c64bd75e5b18c95d8bce648be10ae298f5fd97fe3a6": {
+      "path": "/home/worsch/markitect_project/assets/eb/eb41ad8186ddebf801dd8c64bd75e5b18c95d8bce648be10ae298f5fd97fe3a6.png",
+      "content_hash": "eb41ad8186ddebf801dd8c64bd75e5b18c95d8bce648be10ae298f5fd97fe3a6",
+      "mime_type": "image/png",
+      "size": 16,
+      "created_at": "2025-10-14T13:24:28.557669",
+      "description": "Added to /tmp/tmps0xehpw5/project"
+    }
+  }
 }