Add cppcheck workflow and PS2SDK Codacy shims

[NathanNeurotic]

Summary

• add a cppcheck workflow and helper script configured for Codacy with PS2SDK include paths and shims
• provide lightweight PS2SDK analysis-only headers so cppcheck can resolve SDK types and functions without the full toolchain
• document how to run cppcheck and the include paths used to silence missing-include warnings

Testing

• not run (not requested)

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Codex Task

[codacy-production]

Codacy's Analysis Summary

0 new issue (≤ 0 issue)
0 new security issue

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