enhancement: Polish HTML report visual design and responsiveness

[Daren9m]

Description

General visual polish items identified during first review of the HTML report:

• SVG chart sizing and proportions need tuning for real data distributions
• Donut chart legend alignment
• Mobile nav UX improvements
• Print stylesheet refinements
• Add report generation timestamp in header
• Consider adding a "jump to top" button for the long scrolling report

Acceptance Criteria

• Charts look proportional with real tenant data
• Report is usable on mobile (hamburger nav works, tables scroll)
• Print preview produces readable output