v0.25.2

Documentation maintenance release.

• Fix Read the Docs build failure (conf.py version config shadowed by the importlib.metadata.version import).
• Restore the API Reference example notebook link (symlink moved to docs/examples/).
• Version switcher now reports v0.25.2.
• CI: disable overlapping super-linter v8 validators (Biome) and set persist-credentials: false on checkout (zizmor artipacked).

This tag exists so Read the Docs' stable version rebuilds from code that includes the above doc fixes (the previous v0.25.1 tag predated them).