Brings website up to date with main (18 commits): H1a parse-error
pedagogy, V5/H3/V5a show+help commands, ADR-0043 compound-PK FK,
handoffs 58-59, and the GitHub->Gitea doc scrub (Cargo.toml repository,
CLAUDE.md, ADR-0001 amendment, requirements).
Conflict: docs/adr/README.md. main and website had each created an
ADR-0042 (main: H1a parse-error pedagogy; website: public website &
docs site). Renumbered the website ADR to 0044 (next free after main's
0042/0043) and updated all references (ADR file, plan file, STYLE.md,
astro.config.mjs, README index). Website build verified green.