- Rename `cstring_push` to `cstring_append_ch` and `cstring_push_cstr` to `cstring_append_cstr` for consistent naming with new `cstring_append` function
- Update all callers in lexer and tests to use new function names
- Rename stream `destroy` method to `drop` for consistency with resource management conventions
- Fix potential overflow in string capacity calculation by adjusting growth logic