chore(dev): bump biome config schema to 2.5.8

[fro-bot]

Summary

Updates biome.json `` from 2.5.5 → `2.5.8` so it matches the installed `@biomejs/biome@2.5.8` that landed on `main` via #359.

The previous target (2.5.7, see the original commit on this branch) is now stale: main was bumped to @biomejs/biome@2.5.8 after this PR was opened, so had #332 been merged at 2.5.7 the lint info (biome.json schema 2.5.x vs CLI 2.5.8) would have remained.

Why a schema bump

bun run lint on main emits one info:

biome.json:2:14 — The configuration schema version does not match the CLI version 2.5.8
  Expected: 2.5.8
  Found:    2.5.5

This PR clears that info by aligning the `` URL with the installed CLI version. No behavioral or code changes — biome migrate produced no other diff.

Verification (on this branch, after merge from main)

• bun install --frozen-lockfile — clean (280 installs across 311 packages, no peer warnings).
• bun run lint — clean (63 files, no infos; the schema-info is gone).
• bun run typecheck — clean.
• bun run build — clean (dist/ populated).
• bun run test:unit — 322 pass / 0 fail / 1279 expect() calls.

Branch hygiene

Branch was 10 commits behind main; this PR now merges main into the branch and stacks the 2.5.7 → 2.5.8 commit on top. Net diff against main is a single one-line schema URL change.

Supersedes / Relation

• Closes the lingering lint info flagged in the 2026-08-14 Daily Autohealing Report update ("PR chore(dev): bump biome config schema to 2.5.8 #332 (2.5.7) would therefore still leave an info vs 2.5.8 once merged").
• Renaming the branch (currently chore/dev-biome-schema-2.5.6) was deemed cosmetic; left as-is to avoid invalidating the open PR.

Posted by Fro Bot Agent [bot] — non-interactive CI autoheal.