Optimize oversized decorative README images (currently ~6.3MB each)

[sebastientaggart]

Problem to Fix

The two decorative images shown in the project's README are each about 6.3 MB. They are AI-generated illustrations used purely for visual flair, so they do not need to be high resolution. At their current size they inflate the repository and slow down anyone loading the README.

Why it Matters

Every visitor to the project page on GitHub downloads these images. Large decorative assets waste bandwidth, slow down the page, and bloat the repository's history for every contributor cloning it.

General Approach

Shrink both images to a reasonable display width and re-encode them in a more efficient format better suited for photographic-style illustrations. Update the README to point at the new files and remove the originals.

Complexity

Verification / QA effort: trivial
Open the README on GitHub and confirm both images still render correctly and look visually acceptable.

Acceptance Criteria

• Both README images are under 500 KB each
• Both images still render correctly in the rendered README on GitHub
• README references are updated to the new file paths
• The original oversized files are no longer present in the repository

[sebastientaggart]

Agent Implementation Notes

Files affected:

• .github/assets/readme-header.png (6.3MB, 3588×1184) → replace with readme-header.jpg
• .github/assets/readme-inline-agents-working-with-humans.png (6.4MB, 3588×1184) → replace with readme-inline-agents-working-with-humans.jpg
• README.md lines 21 and 57 — update src= paths to .jpg

Approach:

• Use sips (already available on macOS; cwebp/pngquant/magick are not installed) to resample and re-encode.
• Resample width to 1800px (2× retina at the ~900px GitHub README column). Height scales proportionally.
• Convert PNG → JPEG at quality 80. JPEG is appropriate because the images are photographic/illustrated AI-generated content with no transparency requirements.
• Commands:

  sips -Z 1800 -s format jpeg -s formatOptions 80 \
    .github/assets/readme-header.png \
    --out .github/assets/readme-header.jpg
  

• After re-encoding, git rm the original .png files and update README references.

Expected outcome: each image drops to roughly 150–300KB, a 20–40× reduction, with no perceptible quality loss at display size.

Edge cases / risks:

• None significant. Images are purely decorative; no functional dependencies.
• If JPEG output exceeds 500KB acceptance criterion, drop quality to 70 or reduce width to 1600px.

[sebastientaggart]

Resolution

The two decorative README images were resized to a more reasonable display size and saved in a more efficient format. Each one is now roughly 30× smaller (about 200 KB instead of 6 MB) while still looking the same in the README on GitHub. The oversized originals have been removed from the repository.

See #154 for full technical details.