fix(renovate): biome.json $schema is bumped independently of the embargoed @biomejs/biome package

[krisarmstrong]

Defect (a Renovate rule that keeps biome.json two versions ahead of the linter, fleet-wide)

Renovate bumps the $schema URL in biome.json / ui/biome.json on a schema-only cadence that ignores the npm 7-day embargo gating @biomejs/biome itself. seed git log -3 -- ui/biome.json: 2026-09-13 → 2.5.13 (#2591), 2026-09-06 → 2.5.12 (#2447), 2026-09-03 → 2.5.11 (#2338), each touching only the two schema files while ui/package.json stayed on 2.5.11. Today seed, stem and niac-go all point $schema at 2.5.13 with 2.5.11 installed; CLAUDE.md requires the two to match. Fixing the numbers in the three repos reopens the gap on the next Biome release.

Fix

In default.json, make the schema-URL manager part of the @biomejs/biome update (same group, same minimumReleaseAge) or drop the schema manager and let the package bump carry the URL; then realign the three repos' $schema to the installed version in one lockstep change.

Acceptance

renovate-config-validator default.json passes; after the next Biome release no schema-only PR appears on any UI repo, and jq -r '.devDependencies["@biomejs/biome"]' ui/package.json appears verbatim in each repo's biome.json $schema.

Found by the 2026-09-15 fleet defect sweep (msn-plans msn-defect-sweep-2026-09-15.md).