fix: parse standard UUID text representation

[tianrking]

Description

What does this PR do?

• Correct the final dash position used when parsing the standard UUID text representation (8-4-4-4-12).
• Add a regression test that converts 00112233-4455-6677-8899-aabbccddeeff to the expected 16 bytes.

Why is this change needed?

The parser skipped the last dash two characters too early, so standard UUID strings were decoded with incorrect bytes. This restores compatibility with RFC-style UUID strings used by other libraries and configuration producers.

Validation

• Built the z_utils_test target with CMake/Ninja and MSVC.
• Ran z_utils_test.exe successfully.
• ctest -R '^z_utils_test$' --output-on-failure — 1/1 passed.

Related Issues

Fixes #1229.

Development disclosure

OpenAI Codex assisted with the implementation and test development. The patch was independently cross-reviewed and validated with MSVC as well as a GCC/AddressSanitizer test run.

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Labels: bug

🐛 Bug Fix Requirements

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• Root cause documented - Explain what caused the bug in the PR description
• Reproduction test added - Test that fails on main branch without the fix
• Test passes with fix - The reproduction test passes with your changes
• Regression prevention - Test will catch if this bug reoccurs in the future
• Fix is minimal - Changes are focused only on fixing the bug
• Related bugs checked - Verified no similar bugs exist in related code

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[DenisBiryukov91]

Hello @tianrking . Thanks for your contribution. Could you please sign eclipse eca https://www.eclipse.org/legal/eca/?

[tianrking]

done