Merge dev into main

[admincoderii]

Summary

• add tracked video and carousel example artifacts under example/
• update README with embedded example video, full fufu carousel, goo logo, and cost tracking note
• document docker build fallback and spend reporting
• include recent dev pipeline, browser auth, posting, and spend tracking improvements already on dev

Notes

• output/ remains gitignored
• examples now live under example/ so docs can point at committed artifacts