Add 6 tools for format conversion and optimization extras:
- svg-to-raster: SVG to PNG/JPG/WebP at custom resolution
- vectorize: raster to SVG via potrace (B&W and color modes)
- gif-tools: animated GIF resize, frame extraction, optimization
- bulk-rename: pattern-based file renaming with ZIP output
- favicon: generate all favicon/app icon sizes with manifest.json
- image-to-pdf: combine images into PDF using pdfkit
