feat(ui): easter egg "mag" mode for magnitude notation #125
Description
Display all numbers using order-of-magnitude notation when toggled.
Format: if a value is x, display as "up-arrow floor(log10(abs(x)))" with units preserved.
Examples:
- $5,234.23 -> $ up-arrow 3
- 42 -> up-arrow 1
- $1,000,000 -> $ up-arrow 6
Easter egg toggle key TBD.