#499: fetch homepage release version at runtime

[evgheni7]

Closes #499.

Problem

After a release, the docs homepage keeps showing the previous version (1.0.9 was live as v1.0.8). A release triggers the docs workflow twice — the main branch merge (which resolves the previous version via git describe, since the tag isn't pushed yet) and the tag push (~90s later, correct version). Both create a github-pages deployment seconds apart, and Pages kept the earlier branch-push artifact live even though the tag run deployed last and succeeded. #491 misdiagnosed this as stale JS chunk caching; the served HTML itself is the older build.

Change

• Homepage fetches the latest release from the GitHub API at runtime (useLatestRelease), so the displayed version is correct regardless of which Pages artifact is live. A small FALLBACK_RELEASE covers SSR / first paint and is overridden by the fetch.
• Removed the Resolve release tag + Stamp release placeholders steps and the full-history checkout (only needed for stamping).
• Removed the tags trigger — tags no longer change deployed content, which eliminates the double-deploy race entirely.

Notes

Once merged, a docs deploy (any docs push or a manual workflow_dispatch) will publish and the live site self-corrects to the true latest release.