Improve code reusability across MCP service files

[dusskapark]

This commit introduces utility classes to reduce code duplication and
improve maintainability across Figma MCP service files.

Changes Summary

New Utilities Created

1. ToolRegistrationHelper.kt

   • Reduces boilerplate in tool registration
   • Provides automatic error handling wrapper
   • Simplifies common tool patterns

2. SchemaBuilders.kt

   • Reusable schema builders for common properties
   • Eliminates repetitive JSON schema definitions
   • Provides builders for: nodeId, x, y, width, height, colors, etc.

3. ColorUtils.kt

   • Centralizes color parsing logic
   • Provides RGBA object parsing and formatting
   • Includes default color utilities

4. ParameterExtractors.kt

   • Extension functions for parameter extraction
   • Type-safe required/optional parameter handling
   • Helper functions for building parameter maps

Refactored Files

StyleService.kt

• Original: 229 lines
• Refactored: 143 lines
• Reduction: 86 lines (-38%)

Method-level improvements:

• registerSetFillColor: 63 lines → 27 lines (-57%)
• registerSetStrokeColor: 76 lines → 30 lines (-61%)
• registerSetCornerRadius: 58 lines → 36 lines (-38%)

Documentation

Added comprehensive README.md with:

• Usage examples and migration guide
• Before/after comparisons
• API documentation for all utilities

Impact

These utilities can be applied to all service files in the codebase:

• Estimated 20-30 tool registration methods across services
• Expected total reduction: ~500-700 lines of code
• Improved consistency and maintainability
• Easier to add new tools with less boilerplate

Next Steps

Other services (TextService, ComponentService, LayoutService, CreationService)
can be refactored to use these utilities in future updates.