Fix: Save blend file into stax app template instead of cache directory

Description of fix

File not saved automatically saved to cache directory.

How to test it

With Blender installed as system (not portable)

• Drop a file
• Review it
• Publish

Checklist

Please check if your MR fulfills the following requirements:

• Build was run locally and any changes were pushed
• Lint has passed locally without error
• CHANGELOG.md has been updated
• Branch has been rebased on merge branch

FYI: @dddjef