Stabilize section link resolution determinism

[awakecoding]

Summary

• Make DOCX Strategy A GUID-to-section mapping deterministic (stable ordering, unique-match guards, deterministic fuzzy tie-break).
• Prefer explicit numeric section link text when rewriting GUID anchors during cleanup.
• Make section-number GUID rewrites strict: only rewrite when the target section exists in the document.
• Add regression tests for numeric precedence and strict rewrite behavior.

Validation

• Ran non-live tests: Invoke-Pester ./tests -ExcludeTag Live -Output Detailed
• Result: 5 passed, 0 failed.

Determinism verification

• Triggered Convert and publish twice on the same commit:
  • https://github.com/awakecoding/openspecs/actions/runs/22147837216
  • https://github.com/awakecoding/openspecs/actions/runs/22147834083
• Downloaded both windows-protocols.zip artifacts and compared extracted contents.
• Result: identical outputs (CHANGED=0).