feat(ScoreSetHistogram): add note clarifying clinical controls vs calibration controls

[bencap]

This pull request improves the clarity of how clinical controls (ClinVar annotations) are presented in the score set histogram visualization, ensuring users understand the distinction between clinical controls and calibration controls. The changes add both user-facing documentation and interface notes to prevent confusion.

Enhancements to user guidance and documentation:

• Added an info box to the documentation (visualizations.md) clarifying that clinical controls shown in the histogram are ClinVar entries mapped to the score set, and may differ from the controls used for score calibration. The note emphasizes that the clinical overlay is independent of calibration input data.

User interface improvements:

• Added a conditional note to the ScoreSetHistogram.vue component, displayed when appropriate, informing users that ClinVar annotations in the histogram may not correspond to the calibration control variants, and directing them to calibration sources for details.