- Replace direct php::concat calls with flattened concatenation using parseFlattenedConcat
- Add prepareConcatOperand method to handle proper string conversion for different types
- Implement unified foreach iterator using php::ForeachIterator for both arrays and objects
- Remove separate parseForeachObject method and consolidate iteration logic
- Add support for precompiled headers in GCC-like backends
- Implement PrecompiledHeaderManager for PCH preparation and caching
- Optimize build queue with SourceCompileQueue using largest-first sorting strategy
- Improve progress percentage calculation during compilation
- Add new test case for unified foreach iteration over different iterable types
