[codex] Add tiny landing page

[human-again]

Summary

Adds a no-build static landing page for Orbit in docs/index.html, using the supplied Orbit hero image as the first-viewport visual anchor. The page is ready for GitHub Pages from the /docs folder after merge.

What changed

• Added docs/index.html as a self-contained HTML/CSS landing page.
• Added the supplied image as docs/media/orbit.png.
• Linked the landing page from the README.
• Added a progress.md entry for this iteration.

Validation

git diff --check
.venv/bin/pytest tests/ -q
python3 -m http.server 8765 --directory docs

• git diff --check passed.
• .venv/bin/pytest tests/ -q passed with 21 tests.
• Local static server returned HTTP 200 for / and /media/orbit.png.
• Browser smoke test passed at desktop and mobile sizes with no console warnings or errors.
• The Run the demo CTA scrolls to the quickstart section.

Notes

GitHub Pages still needs to be enabled for the /docs folder in repository settings after this merges. Existing unrelated local changes were left unstaged: .gitignore and .claude/.