Set normalizeAnchor to true by default

[AryaHassanli]

Update Alchemy baller to normalize anchors by default:

• Set NormalizeAnchor to true by default
• Fix a panic
• If NormalizeAnchor is set, when discoballing references, the normalized anchor will be considered even for external files, without necessarily suggesting fix on them.

[gemini-code-assist]

Code Review

This pull request enables anchor normalization by default and updates the anchor label resolution logic in disco/references.go. It also introduces a nil check for the parent element in removeCrossReferenceStutter to prevent potential runtime errors. A review comment suggests simplifying the anchorLabel logic to eliminate redundant type assertions and improve code clarity.