feat: Add custom branch name option for push operations

[Muszkal]

Summary

This PR adds the ability to push to a custom remote branch name while maintaining the current recommended workflow by default. Unlike PR #981, this implementation uses an opt-in toggle that guides users toward best practices while still providing flexibility when explicitly needed.

Motivation

• Quick bug fixes: Working on develop and pushing a small fix to hotfix/issue-123 without creating the branch locally first
• Testing workflows: Creating a feature/new-experiment branch to test changes before pushing to feature/main
• New remote branches: Pushing to branches that don't exist yet or that you don't have local visibility to
• Cross-branch workflows: Experimenting on one branch and pushing to another for review

Benefits

• For Beginners: Default ComboBox guides them to match local/remote branch names (addressing maintainer concerns)
• For Advanced Users: Checkbox provides explicit flexibility when needed (addressing user request)
• Clear Intent: Users consciously choose to use custom names rather than accidentally typing the wrong branch
• Discoverability: Feature is visible but not intrusive

[love-linger]

I've pushed my implementation of this feature.