Improve raster image (PNG/JPG) vectorization quality

[dconroy]

The current browser-based vectorization for converting PNG/JPG to SVG produces low-quality results. It uses a basic canvas tracing method that often loses detail, creates jagged edges, or misinterprets gradients.

Current Behavior:
Uses a simple marching-squares-like algorithm in src/core/imageToSvg.ts.
Traces contours and simplifies paths, but lacks sophistication for handling complex shapes or shading.
Results in "blobby" or overly simplified vector paths that don't represent the original logo well.

Proposed Solution:
Evaluate integrating a more robust client-side tracing library (e.g., potrace port or similar).
Alternatively, investigate WebAssembly-based solutions for better performance and quality.
Consider adding an "advanced mode" or server-side option if client-side limitations are too strict.