v1.2.3

• feat: text weight setting

Appearance gains a Text weight slider under Text size (Light, Regular,
Bold).

Every font-weight in the app's own CSS now resolves through a
five-rung token ramp that [data-weight] shifts as a unit, anchored on
body so elements that never name a weight ride it too.

Three steps because three is all there is: the UI face ships three
static files, and a list only works while emphasis outweighs body text,
so body type can be Regular or Medium and nothing else. Paper resets the
ramp, matching print.ts. Slider now requires an ariaLabel and announces
its readout, as Segmented already did.

Closes #2