refactor(worker): replace transaction any types

[adityabhatkar23]

Description

Replace any transaction client types in the Soroban event worker with Prisma's generated TransactionClient type to improve compile-time type safety.

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🔧 Refactoring (no functional changes)
• ⚡ Performance improvement
• 🧪 Test addition or update

Related Issues

Closes #633

Changes Made

• Added Prisma type imports from the generated Prisma client
• Replaced tx: any with tx: Prisma.TransactionClient in ensureSystemStream
• Replaced tx: any with tx: Prisma.TransactionClient in all Prisma transaction callbacks
• Enabled stronger compile-time validation for transaction-scoped Prisma operations

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed

Test Steps

1. Run npm run build
2. Verify TypeScript compilation succeeds
3. Confirm all transaction callbacks compile successfully with Prisma.TransactionClient

Breaking Changes

Breaking Changes:

• None

Migration Guide:

• No migration required

Screenshots/Demo

N/A

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published
• I have checked for breaking changes and documented them if applicable

Additional Notes

• This is a type-safety refactor only and does not change runtime behavior.
• Using Prisma.TransactionClient allows TypeScript to validate transaction-scoped Prisma operations and catch typos or invalid model access during compilation.