Take reference/breg-api and reference/breg-configuration out of draft

Found in the 0.28.0 pre-release review (2026-09-08). Line references are as of main after #926.

Both pages are `status: draft`, `last_reviewed: unreviewed`, with 12 and 7 inbound links from current pages. `breg-configuration.mdx` is generated from schema descriptions; most properties added since v0.27.0 carry no `description` on their schemars types and render as blank rows, and `actions[].requires[].equals` never renders because its subschema is the bare boolean `true` (`registry-project.schema.json:502`), which `docs/site/scripts/configuration-reference.mjs:306` drops.

Proposed: add `description` to the schemars types, teach the walker to render boolean subschemas, then review both pages and set their review record.

Start by reading docs/site/scripts/configuration-reference.mjs around line 306 and inspecting registry-project.schema.json:502, then trace the schemars types that supply the configuration descriptions. Done means the blank properties and actions[].requires[].equals render correctly, both reference/breg-api and reference/breg-configuration are reviewed, and their review records no longer show as unreviewed.

Written by the indexing model from the issue text.