Spin the refresh icon in place

[MathiasWP]

The rotating "refresh endpoints" spinner drifted off centre as it turned.

text-3 is 0.75rem, and the root font-size is 13px, so presetIcons' 1.2em box came out 11.7px. A mask that size resamples to a slightly different centre at each angle, so the icon orbited rather than spun in place. Both refresh-cw icons in the sidebar now use a whole-pixel w-12px h-12px box.

Measured in headless Chrome with this repo's generated UnoCSS — centroid of the rendered icon across 12 angles:

box	1x	2x
11.7px (text-3)	0.41 × 0.61 px drift	0.33 × 0.31 px
12px (w-12px h-12px)	0.06 × 0.04 px	0.04 × 0.05 px

pnpm check passes. Measured in Chromium rather than the WKWebView the app actually ships in, but the cause — a fractional-pixel mask box — is engine-independent.