feat(commands): introduce ricecoder-commands crate with command manag…

[moabualruz]

…ement system

• Create new ricecoder-commands crate with comprehensive command management infrastructure
• Implement CommandManager for registering, validating, and executing custom commands
• Add CommandRegistry for maintaining command definitions and metadata
• Implement CommandExecutor with template substitution and argument injection
• Add OutputInjection system for dynamic output formatting and variable substitution
• Create CommandConfig for loading and managing command configurations from YAML/JSON
• Implement error handling with custom CommandError types
• Add CustomCommandsStorage integration for persisting commands to storage layer
• Refactor custom.rs in CLI to use new ricecoder-commands crate instead of inline implementation
• Create custom_storage.rs module for CLI-specific storage operations
• Add comprehensive property-based tests for command execution and configuration
• Update Cargo.toml workspace to include new ricecoder-commands crate
• Remove property_custom_commands.rs tests (functionality moved to new crate)
• Update storage config documents and loader for command persistence
• Consolidate 2700+ lines of custom command logic into modular, reusable crate architecture