Side-by-side theme comparison (litmus-gjmg)


Status	Done · `archived`
Type	Feature
Priority	normal
Parent	(litmus-iiek)

Side-by-side theme comparison: same scene rendered with two different themes.

Summary of Changes

Added side-by-side theme comparison:

/compare/:left/:right route renders all scenes in two themes side by side
Theme selector dropdowns for switching comparison targets
“Compare…” link on each theme detail page
Responsive CSS: two columns on desktop, stacked on mobile