Build IronPhoenix Pages website with local Bulma assets

[KnightStackSys]

Summary

The GitHub Pages folder previously contained only its custom-domain file. Add a responsive Bulma website introducing IronPhoenix, four-player Teams rules, PhoenixNet, and build/search instructions sourced from the repository README.

• Vendor Bulma 1.0.4 locally with its MIT license; no package dependencies or build step.
• Add a dark theme, cross-board illustration, mobile navigation, accessible focus states, and copyable commands.
• Include website maintenance and preview instructions.
• Preserve docs/CNAME (iphoenix.art) byte for byte and leave existing workflows and deployment configuration unchanged.

Validation

• JavaScript syntax and Git whitespace checks passed.
• HTML parsing, unique IDs, local assets, and section anchors checked.
• DOM-stub checks passed for navigation toggle, Escape/focus restoration, closing the menu on selection, command copying, and the 160-square board with 64 pieces.
• Bulma version/license and unchanged CNAME/workflows verified.
• Browser preview could not connect to the local HTTP server in this environment. Visual layout, responsive overflow, and browser clipboard behavior still need manual verification; DOM-stub checks are not browser tests.