[N/A] Update PR template

[Alomir]

Summary

• What: Update PR template to more closely match desired workflow

How was this change tested?

Proposed template was used to create this PR

Reproduction steps

N/A

Related issues

• N/A

Checklist

• Related issues are listed above
• PR title has the issue number in it ("[#] <concise description of proposed change>")
• Tests added for new features
• Documentation updated (if applicable)
• docs/CHANGELOG.md updated with noteworthy changes
• Code formatted with clang-format (run git clang-format if needed)

For model structure changes:

• Removed \fraktur font formatting from docs/model-structure.md for implemented features

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Note: See CONTRIBUTING.md for additional guidance. This repository uses automated formatting checks; if the pre-commit hook blocks your commit, run git clang-format to format staged changes.