Diverse changes to sdkdocs generation

[AlexejPenner]

Clean up and harden SDK docs build

Summary

• Fix migration side-effect during docs builds: Guard run_migrations() in env.py with DISABLE_DATABASE_MIGRATION env var instead of deleting source files before building. Removes fragile rm -rf of migration files from generate-docs.sh.
• Prevent backports from stealing the latest docs alias: publish_api_docs.yml now compares the version being built against the highest git tag and only applies the latest alias if it's truly the newest release.
• Add version validation in CI: Rejects non-semver branch names with a clear error before publishing docs.

Additional fixes

• Fix Plausible analytics domain (apidocs.zenml.io → sdkdocs.zenml.io)
• Disable broken "Edit this page" link
• Update cli.md from deprecated mkdocstrings selection/rendering syntax to modern options: block
• Fix broken --ignored_modules argparse flag in mkdocstrings_helper.py (type=List[str] → nargs="*")
• Remove dead loop in mkdocstrings_helper.py
• Add !^migrations$ filter to mkdocs.yml to hide migrations from rendered SDK docs
• Add DISABLE_DATABASE_MIGRATION=1 to serve_api_docs.sh
• Simplify docs/README.md local build instructions to just bash scripts/serve_api_docs.sh
• Fix deprecated echo ::set-output → $GITHUB_OUTPUT in CI workflow

[github-actions]

✅ No broken links found!

[github-actions]

Documentation Link Check Results

✅ Absolute links check passed
✅ Relative links check passed
_{Last checked: 2026-03-30 13:56:00 UTC}

[schustmi]

Maybe also rename this file to sdk_docs?

[github-actions]

⚠️ This PR has been inactive for 2 weeks and has been marked as stale.
Timeline:

• Week 2 (now): First reminder - PR marked as stale
• Week 4: PR will be automatically closed if no activity
  Please update this PR or leave a comment to keep it active. Any activity will reset the timer and remove the stale label.