chore(): Bump to 25.6.9

[benflexcompute]

Note

Finalizes the 25.6.9 release by updating version strings and test references.

• Sets __version__ to 25.6.9 and pyproject.toml version to v25.6.9
• Updates all test fixtures and reference JSONs version fields from 25.6.9b0 to 25.6.9
• Adjusts tests/test_current_flow360_version.py assertion to 25.6.9

^{Written by Cursor Bugbot for commit 7c15ea8. This will update automatically on new commits. Configure here.}