7. Add explanatory captions for Px, Fx, and Hybrid outputs

[opeyemibami]

Description

Visual outputs (Px heatmap, Fx attention, Hybrid score) can be difficult to interpret without reading the paper.

This issue proposes adding short explanatory captions to clarify what each output represents, without renaming outputs.

Scope

• Add one-line descriptions in notebooks and documentation
• No UI redesign
• No renaming of existing outputs

Acceptance Criteria

• Descriptions appear alongside visualizations
• Terminology remains consistent with the paper

Notes / Constraints

• Avoid oversimplification
• Keep explanations concise and technically accurate