Fix mixed row inference for PDOStatement::bindValue() + execute()

[vaielab]

Summary

Fix row inference for PDO statements that use bindValue() before execute().

The issue caused iterated rows to be inferred as mixed instead of the expected typed array shape.

Changes

• add regression coverage for the bindValue() path
• update PdoStatementExecuteTypeSpecifyingExtension to preserve row typing after execute()

Result

foreach ($stmt as $row) now keeps the expected inferred array type for supported bindValue() usages.

[vaielab]

I think it's also related to #770

[staabm]

thanks for the PR. I do atm not have time to look into it. I will come back to it.