docs: Convert core documentation to AsciiDoc format

Convert README, LICENSE_TLDR, CLAUDE, CONTRIBUTING, and CODE_OF_CONDUCT
from Markdown to AsciiDoc format per RSR Rhodium requirements.

- Update all documentation with ReScript + WASM architecture
- Reflect dual MIT/AGPL licensing
- Document Git SSH-only operations
- Update build system to use justfile (no Node.js/npm)
- Maintain AsciiDoc format except SECURITY.md, humans.md, LICENSE.txt, funding.yml

Part of RSR Rhodium Standard v2.0 compliance.

Author: claude