Sven UX video doc (plan)
Add [docs/SVEN_UX_VIDEO_SCRIPT.md](docs/SVEN_UX_VIDEO_SCRIPT.md) that **mimics [docs/UNIT_TEST_VIDEO_SCRIPT.md](docs/UNIT_TEST_VIDEO_SCRIPT.md)** section-for-section: same headings pattern, timecodes, Narration blockquotes, On-screen / Actions bullets, per-scene **Screenshot** filenames, **Key Phrases**, **Screenshot Checklist** table, **Technical Notes**, plus Sven-specific humor (Bootstrap `mr-2` vs BS5 punchline).
aiagentcursor
