fix(author): enforce semver matching and numeric template ordering

[Acuspeedster]

Types of changes

• Hot fix (emergency fix and release)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Documentation (change which affects the documentation site)
• Breaking change (fix or feature that would cause existing functionality to change)
• Release (develop -> main)

Quality assurance (all should be covered).

• My code follows the code style of this project.
• Documentation for my change is up to date?
• My PR meets testing requirements.
• All new and existing tests passed.
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Summary

Fix template version parsing and ordering so template directories are identified strictly by semantic version and latest version selection is numeric (not lexicographic).

Changes made:

• TEMPLATE_VERSION_REGEX is now strict semver (^X.Y.Z$) instead of a loose pattern.
• TemplateVersioning.update_template_folder_structure() now uses strict full-match checks for version folders.
• TemplateVersioning.get_all_versions_for_task() now includes only strict semver directory names.
• TemplateVersioning.get_latest_version_for_task() now sorts versions numerically by (major, minor, patch).
• TemplateVersioning.is_valid_version() now uses the shared strict regex constant.
• Added regression tests for:
  • numeric ordering (10.0.0 over 2.0.0)
  • strict semver-only directory filtering.

Files updated:

• trestle/common/const.py
• trestle/core/commands/author/versioning/template_versioning.py
• tests/trestle/core/commands/author/versioning/template_versioning_test.py

Validation run:

• pytest tests/trestle/core/commands/author/versioning/template_versioning_test.py -q --basetemp .pytest_tmp
• Result: 9 passed

Key links:

• Sonar coverage

Before you merge

• Ensure it is a 'squash commit' if not a release.
• Ensure CI is currently passing
• Check sonar. If you are working for a fork a maintainer will reach out, if required.