fix(string): Fix character length limit and unnecessary allocation in AsciiString::toLower(); add AsciiString::toUpper()

[xezon]

Merge with Rebase

This change fixes the character length limit (MAX_FORMAT_BUF_LEN) and unnecessary allocation (when string was already lower) in AsciiString::toLower() and implements a AsciiString::toUpper() as well.

UnicodeString does not have a toLower function.

TODO

• Add pull id to commits

[greptile-apps]

Greptile Summary

Updates AsciiString case conversion to operate in place without a fixed-length temporary buffer and adds the corresponding uppercase API.

• Reworks toLower() to avoid allocation when conversion is unnecessary.
• Adds toUpper() with equivalent copy-on-write behavior.
• Casts bytes to unsigned char before every ctype call, resolving the previously reported invalid-input-domain issue.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
Core/GameEngine/Include/Common/AsciiString.h	Declares the new AsciiString::toUpper() API.
Core/GameEngine/Source/Common/System/AsciiString.cpp	Implements allocation-aware in-place case conversion and safely supplies unsigned-byte values to ctype functions.

_{Reviews (2): Last reviewed commit: "chore(string): Implement AsciiString::to..." | Re-trigger Greptile}

[Skyaero42]

Looks good