* Studio: register text-ui tokens with tailwind-merge so cn keeps them
Stock tailwind-merge classifies text-ui-* as a text color, so cn() dropped
the size class whenever a color utility followed it in the same call. The
element then fell back to the unscaled 16px root font, which made hub tabs
and capability pills look oversized at small UI font sizes. Extend the
merge config so text-ui-* and leading-ui-* resolve as font-size and
line-height groups, and cover the failure in the contract and Playwright
regression tests.
* Studio: rename the Models page to Model hub
Page heading, sidebar navigation label in all locales, and the chat
download toasts that point at the tab.