BYOC hero: remove title text from the image

[NicholasKissel]

Removes the "Introducing Rivet BYOC" heading from the rendered hero (render-byoc-hero.ts) and recentres the diagram vertically. Bumps the post's image.png?v=6 cache-buster.

Before merging, re-render and upload the new hero so ?v=6 resolves to the title-less image:

pnpm render-byoc-hero -- --output-dir /tmp/byoc-hero
AWS_ACCESS_KEY_ID='op://Engineering/rivet-assets R2 Upload/username' \
AWS_SECRET_ACCESS_KEY='op://Engineering/rivet-assets R2 Upload/password' \
op run -- aws s3 cp /tmp/byoc-hero/image.png \
  "s3://rivet-assets/website/blog/2026-09-15-introducing-rivet-byoc/image.png" \
  --endpoint-url https://2a94c6a0ced8d35ea63cddc86c2681e7.r2.cloudflarestorage.com

Thread: https://ampcode.com/threads/T-01a0a1bf-48c6-77f8-b65d-0b681d9f18a9

[the-company-company]

🔴 1 high-severity finding

_{Reviewed commit 9336821.}

[the-company-company]

🔴 High · Publish the regenerated hero before switching its cache key

The new query string does not select a new asset: both image.png?v=5 and image.png?v=6 currently return the same 74,197-byte PNG with SHA-256 4a468e…62910. That image still contains the removed title, so the live post will not receive this change even after the frontmatter cache bust.

Regenerate with the updated renderer and upload the resulting image.png to website/blog/2026-09-15-introducing-rivet-byoc/ before changing the cache key.

[the-company-company]

✅ No issues found

_{Reviewed commit 46e0d75.}