feat(MAX-570): add OSS demo-first content bundle

[maxtechera]

Summary

• add the MAX-570 OSS demo-first content bundle with 3 reels, hook library, long-form script, newsletter draft, and README CTA copy
• update README with demo-first CTA language aligned to the open-source -> newsletter -> course funnel
• include proof artifacts: rendered markdown HTML/screenshot and a vertical MP4 teaser for attachment use

Proof

• Bundle: docs/marketing/MAX-570-oss-demo-first-content-bundle.md
• Proof pack: artifacts/MAX-570/proof-pack.md
• Screenshot: artifacts/MAX-570/rendered-github-markdown-screenshot.png
• MP4: artifacts/MAX-570/MAX-570-oss-demo-first-teaser.mp4

Checklist

• Content bundle added
• README CTA updated
• Proof artifacts included
• No secrets in diff

Closes MAX-570

[linear]

MAX-570 Reel scripts — /ship OSS demo-first content