feat: implement visual schematic rendering system

[lamaalrajih]

Description

This PR adds major new visualization capabilities for debugging and testing KiCad schematics, providing both KiCad CLI integration and a mock renderer fallback for development environments.

special thanks to @laurigates!

Core features:

• KiCad CLI SVG export with automatic macOS path detection
• Mock renderer fallback when KiCad CLI is unavailable
• SVG to PNG conversion using cairosvg
• Visual comparison tools for before/after screenshots
• Comprehensive visual testing utilities

New Files Added:

• kicad_mcp/tools/visualization_tools.py - Main visualization MCP tools
• kicad_mcp/utils/mock_renderer.py - Fallback renderer for development
• kicad_mcp/utils/visual_testing.py - Visual testing and comparison utilities
• test_visualization_standalone.py - Comprehensive test suite

Key Capabilities:

• export_schematic_svg() - Export .kicad_sch to SVG using CLI or mock
• convert_svg_to_png() - Convert SVG files to PNG images
• capture_schematic_screenshot() - End-to-end screenshot generation
• create_visual_comparison() - Side-by-side comparison images
• Mock renderer generates schematic visualizations without KiCad

Related Issue(s)

n/a

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring (no functional changes)
• Other (please describe):

Testing Performed

• Added new unit tests
• Manually tested on macOS
• Manually tested on Windows
• Manually tested on Linux
• Integration tested with Claude Desktop or other MCP client

Screenshots/Output

Checklist

• My code follows the project's coding style
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation to reflect my changes
• My changes generate no new warnings or errors
• I have checked that my changes work on all supported platforms
• New and existing unit tests pass with my changes

Additional Notes

Dependencies Added:

• cairosvg>=2.7.0 - SVG to PNG conversion
• Pillow>=10.0.0 - Image processing
• playwright>=1.40.0 - Browser automation (optional)

Benefits:

• Visual debugging of component positioning issues
• Screenshot verification of wire connectivity
• Development workflow without requiring KiCad installation
• Foundation for visual regression testing in CI