Fix tour layout, synthesis reliability, and cache safety

fix: diagram header/tabs cramping on mobile

feat: mobile polish — touch scroll, pinch-zoom, responsive onboarding

fix: zoom toward cursor in diagram and explore views

fix: proportional scroll zoom in diagram and explore views

design: premium UI polish + agent reliability fixes

refactor: distinct type colors across the spectrum — each node type own hue

fix: unified chain glow color on hover — entire connected subgraph shares the source node's color

fix: consistent chain glow across all diagram views

fix(diagrams): strong hover glow on all diagram types — Architecture, Class, Explore

fix(ui): remove top glow bar from diagram cards + purge warm card colors

feat(ui): Blueprint Dark — complete color system rebuild

Major feature: interactive diagrams, MCP integration, and bug fixes

checkpoint: pre-UI-overhaul state