pkgs: hero SVGs, bismuth flags, croft-click devlog

Hero SVGs. Added OG-compliant hero SVG images to all five project cards: malachite-web, opal-web, jasper-web, bismuth-web, and tourmaline. Tourmaline card now leads with Teal.fm branding.

Bismuth flags. Added --frontmatter and --output flags to the fetch subcommand for controlling YAML frontmatter inclusion and output directory. Web package got document fetching, conversion options, and accessibility fixes.

croft-click. Added devlog project to croft-click (the subdomain registry). Added Bismuth logo PNG asset.