docs

docs: frontmatter editor — .constraints.md, /api/note/constraints, Changes button

docs: dev-wikilinks — add data-autolabel display label resolution section

docs: codeblock gate architecture — two models, 403→silent, front admin, nav destination-gated

docs: #todo note — config repo sync endpoint hardcoded to master, should be nb-config

docs: codeblock access gates — user section in CODEBLOCKS, impl section in dev-codeblocks