Fix the 71 positional references failing Index Integrity

[FlorianBruniaux]

Evidence

Index Integrity fails on main at https://github.com/FlorianBruniaux/claude-code-ultimate-guide/actions/runs/33397436525. scripts/resync-reference-yaml.py --check reports 71 broken references against a maximum of 0: 26 MEDIUM, 44 LOW and 1 UNKNOWN.

Acceptance criteria

• Classify every reported reference.
• Replace positional references with stable anchors where the landing index contract permits it.
• Preserve protected quantities and explicitly justified bare integers.
• Make scripts/resync-reference-yaml.py --check pass with max-broken 0.
• Confirm Index Integrity is green on main.