feat(docs): add bootcamp promo video to the landing page

[docktermj]

What and why

Adds the two-minute bootcamp promo video to the landing page, so a potential Bootcamper can see
the bootcamp in action before choosing a platform.

File	Purpose
docs/index.html	New "The bootcamp in two minutes" section (#watch) after the hero; a Video nav link; the light sections after it swap white ↔ off-white so the grounds still alternate
docs/index.css	.promo rule: full width up to 56rem, 16:9, rounded, obsidian background, the same shadow as the tiles and cards
docs/video/senzing-bootcamp-promo.mp4	The promo: 2:00, 1920×1080 H.264 with AAC audio, 21.7 MB, captions burned in
docs/images/senzing-bootcamp-promo-poster.jpg	Poster frame taken from the video's end card at 1:55, 1280 px, 40 KB

Choices

• No autoplay. The video has sound and is 21.7 MB, so it plays only on demand, with controls.
  preload="metadata" fetches only its length up front.
• Fallback: browsers that can't play MP4 get a download link.
• Accessibility: captions are burned into the picture, so there is no separate <track>;
  the aria-label says the video has on-screen captions.
• Every path is relative, so the page still resolves under /bootcamp/. Still no JavaScript and
  no new external resources.

Checks

• cspell: 0 issues.
• Headless Chrome at 1280 px and 360 px: the video scales to fit, shows 0:00 / 2:00, and there
  is no horizontal scroll at 360 px.

[github-actions]

🤖 Claude Code Review

I reviewed the diff and reported six findings. I only read the files and did not run the spellcheck or open the page in a browser.

Code quality and security: no blocking problems

• The new .promo CSS follows the existing style and uses the existing custom properties.
• The video and poster paths are relative, as CLAUDE.md requires.
• The video adds no third-party resources and no JavaScript.
• Alternating the section backgrounds after inserting the new section is done correctly.
• width: 100% keeps the video within 360 px, so I expect no horizontal scroll.
• The diff contains no credentials, no license files and no AQAAAD strings.

Findings

• ❌ Captions (docs/index.html:66): the aria-label says "on-screen captions", but the captions are burned into the video. There is no <track kind="captions"> and no transcript, so screen-reader users get nothing.
• ❌ Large binary (docs/video/senzing-bootcamp-promo.mp4): the 21 MB file is committed to git, so every re-encode adds another ~21 MB to history. The fallback text hard-codes "21 MB" (index.html:67), which goes stale when the video is replaced.
• ❌ CLAUDE.md Layout section (.claude/CLAUDE.md:23): it doesn't list the new docs/video/ directory.
• ❌ Changelog (CHANGELOG.md:10): the Unreleased section is empty, so the new video section isn't recorded.
• ⚠️ Unverified length (docs/index.html:63): the heading says "in two minutes", and I did not check the video's actual length against it.
• ⚠️ Cosmetic (docs/index.css:380): .promo sets both height: auto and aspect-ratio, and max-width with display: block leaves the video left-aligned.

Testing
No tests are expected for this static page.

Documentation
Markdown was not changed in the diff, so CommonMark and prettier formatting are not affected. The README and API docs don't need updating.

Automated code review analyzing defects and coding standards