Codifies the fix for the ADR-0042 cross-branch collision (resolved this
merge by renumbering the website ADR to 0044): ADR numbers are assigned
when a branch merges to main, not at creation. On a branch, draft under
a placeholder (ADR-XXXX title / draft-<slug>.md filename); main's
docs/adr/README.md is the single source of truth for the next free
number.
- ADR-0000: new "Numbering discipline" section.
- CLAUDE.md: pointer to it from the documentation-discipline note.
claude@clouddev1
9e774b2dfa