* chore: migrate to flairup 1.1.1-rc.1 (exact pin)
* Fix nav icon background under flairup 1.1.1-rc.0 cx contract
Replace background:none reset with backgroundColor:transparent so the
Button class no longer shares conflict keys with the category sprite's
background-image and survives cx() composition.
* Fix invisible native emoji under flairup 1.1.1-rc.0 cx contract
Compose the font-size:0 reset before the real size so cx() keeps the
size: later class wins same-property conflicts.
* chore: promote flairup pin to final 1.1.1
* Bump version to 4.20.0 (gradual exposure of flairup 1.1.1)