Fixes #XXX

Changes

• Removed mutation of the original Transaction object during gas estimation
• Introduced safe cloning via Transaction.CopyTo() to solve TODO in GasEstimator.TryExecutableTransaction

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature
• Breaking change
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: n/a

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No

Notes on testing

Existing coverage is sufficient. This change preserves logic and only affects internal transaction handling during estimation.

Documentation

Requires documentation update

• Yes
• No

Requires explanation in Release Notes

• Yes
• No

Remarks

This PR resolves the inline // TODO: Workaround to not mutate the original Tx by introducing a proper, non-mutating transaction cloning process using Transaction.CopyTo(). This improves safety and code clarity in gas estimation routines.