Add vector extension support for .svg and route SVG files through npx svgo before raster compression.
Keep behavior fail-safe: missing npx/svgo or non-zero svgo exit returns None and preserves existing flow.
Extend tests for SVG discovery, SVG routing priority, and missing npx handling.
Co-Authored-By: Abacus.AI CLI <agent@abacus.ai>
Introduce compress_image_with_routing and compress_raster_image to prepare extensible backend routing while keeping existing behavior unchanged.
Add unit test that verifies routing currently delegates to raster compressor.
Co-Authored-By: Abacus.AI CLI <agent@abacus.ai>