Bytecode compat - Align Call/Return and Expression Emission

[youknowone]

Background:
Frequent mismatches show CALL/LOAD_CONST, FORMAT_SIMPLE/BINARY_OP, and related
expression-sequence rewrites, indicating divergence in call and expression lowering
order.

Task:

• Review bytecode generation around function/method calls, unary/binary operations, and
  formatted string/format-like code paths.
• Ensure RustPython emits equivalent pre/post stack state for:
  • CALL argument preparation
  • BINARY_OP classification
  • FORMAT_SIMPLE handling
• Keep instruction-level stack effect consistent with CPython for equivalent source
  snippets.

Acceptance criteria:

• Mismatch counts for pairs involving CALL/BINARY_OP/FORMAT_SIMPLE decrease.
• No regression in small syntax/format-heavy modules (e.g., string formatting tests, AST
  unparse paths).