Implement SAVEPOINT support for nested transactions

[Copilot]

• Identify missing AST imports in main Red.rakumod file
• Fix TransactionContext Promise handling that could cause hanging
• Add proper AST imports to test files
• Fix test array access patterns for translate method results
• Validate savepoint implementation for proper delegation
• Verify tests pass without hanging
• Address any remaining issues found during testing

---

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.

[FCO]

It seems a file is missing to be added and there are tests hanging... @copilot could you take a look, please?

[Copilot]

It seems a file is missing to be added and there are tests hanging... @copilot could you take a look, please?

I've addressed both issues:

Missing file: The savepoint AST classes needed to be imported in the main Red.rakumod file. Added imports for Red::AST::Savepoint, Red::AST::RollbackToSavepoint, and Red::AST::ReleaseSavepoint.

Hanging tests: Fixed several issues that could cause hanging:

1. Removed unnecessary Promise handling in TransactionContext that could block
2. Added missing AST imports to test files so they can access the classes
3. Fixed test array access patterns - translate() returns a Pair, not an array

The changes are in commit 0136e13. The implementation should now work without hanging and with all required files properly included.