Fix OpenQASM 3 for loop variable type annotation (gh-12866)

[akhil-102]

I've fixed this issue! The OpenQASM 3 exporter now correctly includes type annotations for for-loop variables.

What was fixed:

• Added int type annotation before loop variable names in for-loop statements
• Updated all existing for-loop tests to expect the correct format

Before:

for _ in {0, 1} {
  x q[0];
}

After:

for int param in {0, 1} {
  x q[0];
}

The fix ensures compliance with the OpenQASM 3 specification, which requires explicit type annotations for loop variables. This works for both named parameters (like param) and unnamed parameters (which use _).

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