feat: Add automatic rollback on upgrade failure

[psywarrior1998]

This pull request introduces a critical safety feature to protect the user's environment. If a package upgrade fails for any reason (e.g., network error, compilation failure), the tool will now automatically attempt to revert that package to its previously installed, stable version.

This prevents a failed upgrade from leaving the environment in a broken or inconsistent state.

Technical Implementation:

• The core upgrade_package worker function now wraps the upgrade attempt in a try...except block.
• The package's original version is recorded before the upgrade is attempted.
• If the upgrade fails, the except block triggers a pip install --force-reinstall <package>==<original_version> command to perform the rollback.
• A new UpgradeStatus enum has been introduced to provide more granular results (SUCCESS, ROLLBACK_SUCCESS, ROLLBACK_FAILED).
• The final summary report has been enhanced to clearly display the outcome of all operations, explicitly highlighting any rollbacks or critical failures.
• A --no-rollback flag has been added for advanced users who wish to disable this functionality.