fix(templates): add cottontail-tmp/ to all template .gitignore files

Summary

Adds cottontail-tmp/ to .gitignore in all 31 project templates to prevent accidental commits of runtime-generated temporary files.

Changes

• Updated .gitignore in all templates under templates/ directory
• Added cottontail-tmp/ entry to exclude the temporary directory created by the cottontail runtime

Testing

• Verified all 31 template .gitignore files now include cottontail-tmp/
• Confirmed no other files were modified

Related Issues

Closes #539