9e774b2dfa
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.