Summary

Audit and update frontmatter metadata across non-OpenAPI MDX pages to improve search snippet quality and remove duplicates.

Changes

• Rewrote description on 41 pages so each is unique, specific, and 130–155 characters (was 40–76 characters previously, with three pages sharing duplicates across admin-api/ and api-reference/).
• Converted seven guide titles from Title Case (e.g. "How To Build A Streaks Feature") to sentence case (e.g. "How to build a streaks feature") to match the repo style.
• Did not touch OpenAPI operation pages — all referenced operations supply a description in openapi/admin.yml / openapi/application.yml, so adding frontmatter description would override the spec.
• No content, navigation, or OpenAPI spec changes.

Context

• All titles were already under 60 characters; none used a PageType - Name boilerplate pattern.
• All non-OpenAPI pages already had title and description fields present — issues were length and uniqueness, not absence.
• mint validate and mint broken-links both pass.