Avoid unnecessary content rendering on list pages

[plx]

Summary

The list pages are eagerly rendering full content for entries even though only frontmatter-derived card data is used. This introduces unnecessary build-time work and memory churn.

Affected files:

• src/pages/index.astro
• src/pages/briefs/index.astro
• src/pages/briefs/[category].astro

Why This Matters

Calling item.render() for list pages that only show titles/descriptions does extra markdown/MDX processing with no user-visible benefit.

Proposed Strategy

• Remove Promise.all(... item.render()) from list pages where <Content /> is never used.
• Keep collection entries as-is and pass them directly into card helper functions.
• Preserve existing sort/filter/slice behavior.

Done Criteria / Validation

• rg -n "await item\.render\(" src/pages/index.astro src/pages/briefs/index.astro 'src/pages/briefs/[category].astro' returns no matches.
• npm run build passes.
• npm run qa passes.
• No visual regression on home/brief list pages.