Remove internal v1.3 release work artifacts

[maxliebscher]

Summary

• removes unreferenced internal v1.3 screenshot captures, QA reports, and prototype/demo HTML files that were accidentally included in the release merge
• keeps only the 10 README gallery JPGs, release notes, standalone release HTML, release image, and final app files
• removes one internal future-feature spec that was not part of the public v1.3 release surface

Verification

• README image link check: 10/10 local assets present
• git diff --check
• verified remaining assets/screenshots contains only the 10 README JPGs