Fix BinaryOp '=' overlap with VariableAssignment

[dhruvv16-hash]

Description

Implemented the fix for BinaryOp handling "=" overlapping with VariableAssignment, so assignment is now handled only through VariableAssignment.

Removed assignment handling from BinaryOp in src/irx/builders/llvmliteir.py.
Added a safety guard so BinaryOp("=") now raises:
Assignment '=' should not be handled in BinaryOp. Use VariableAssignment instead.
Kept assignment handling in VariableAssignment, which remains the only valid assignment path.
Added a regression test in tests/test_binary_op.py to verify BinaryOp("=") is rejected.
Added a regression test in tests/test_variable_assignment.py to verify VariableAssignment still updates the variable correctly and print(x) works.

This is a codegen-only change and does not alter parser/frontend behavior.

Fixes: #265

Comments

Please verify that assignment is only handled through VariableAssignment.
Ensure other binary operators like +, -, *, /, and comparisons still behave normally.
The BinaryOp("=") guard is intentional to prevent duplicated codegen paths and preserve the intended language design.

Checklist:

• The code follows the project style.
• Regression tests were added.
• Tests were fully executed locally.

Testing note:
Local automated test execution is still blocked on this machine by environment/dependency setup issues, not by a known code failure.

Before

After

[m-akhil-reddy]

hi @dhruvv16-hash ,
i am presently working on this issue #265

[dhruvv16-hash]

Hi @m-akhil-reddy,
Thanks for letting me know! I’ve already worked on this and opened a PR (#268) addressing the issue.
It removes '=' handling from BinaryOp and centralizes it in VariableAssignment.
Would be great to get your thoughts on whether this aligns with the intended approach.

[xmnlab]

@dhruvv16-hash , as a good practice always ask if someone else is already working on an issue. it helps us to keep the community a a nice and friendly space for collaboration.
please don't add the artificts folder.