Add eight live investor profiles, flat design and change charts

[lch262]

Summary

• add live Bridgewater, Pershing Square, Appaloosa and Duquesne manager profiles
• expand the public investor directory to eight SEC-backed institutions
• introduce an Apple-inspired flat visual system with Lucide line icons
• add an interactive quarterly change line chart to every manager profile
• support percentage/share-count switching, hover and keyboard detail inspection

Data notes

• charts are derived from each manager's adjacent-quarter SEC snapshot
• new and exited positions use +100% / -100% action markers in percentage mode
• Pershing Square uses the latest available filing for 2026-03-31
• Duquesne reported-value units are normalized and explicitly disclosed on the profile

Verification

• frontend lint passed
• production build passed
• 22 rendered HTML route tests passed, including all eight chart-enabled manager pages
• 31 Python SEC pipeline tests passed