Fix label colours for ColorPicker components

Add style/cancellation options, colour picker, transparency fixes, label colours

Add Philatelist theme, fix dark backgrounds, halftone tuning, export collection

Fix cancellation font size too small causing PIL division by zero

Add cancellation postmark style, fix gallery hover, fix engraving bytes

Fix engraving: pass image as bytes to HF inference API

Fix engraving: force hf-inference provider for instruct-pix2pix

Reduce halftone dot size for finer, more separated dots

Add halftone dot effect style

Surface engraving API errors instead of silent fallback

Cover-crop images to fill stamp area regardless of aspect ratio

Move css param to launch() for Gradio 6 compatibility

Use HF Inference API for engraving style via Space secret

Add engraving style via ZeroGPU, polish UI colours