Handle SVG clip paths, masks, and filters

[mezotv]

Problem

Kiwi does not currently represent SVG clipPath, masks, filters, shadows, or blend modes.

Impact

Logos and marketing illustrations that rely on clipping or visual effects import with visible extra geometry or missing effects.

Suggested scope

• Start with clipPath support for common path/rect clips.
• Define fallbacks for masks and filters when exact Figma mapping is not practical.
• Add fixture SVGs that demonstrate clipped logo shapes and masked fills.

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Linear issue: NOT-75