feat(icons): shrink the Android adaptive mark 25%, give old square launchers the full-bleed master

The adaptive foreground's asterisk grazed the round mask's safe zone. Scale the
foreground mark 0.75 about the icon centre (25% smaller, the letter-to-star
arrangement unchanged) so it sits well inside the 61% safe zone. Independently,
the legacy square ic_launcher.png now renders the full-bleed master instead of
the safe-zone composite, so old Android (< API 26) shows a large mark rather
than a shrunk one; the legacy round icon keeps the safe-zone composite (a round
mask would clip the master's corner star). Regenerate the layer set, Android
res and the brandbook foreground previews; update ICON_BRANDBOOK.md / ICONS.md.

assets/icons/brand/build-icon.mjs

@@ -33,8 +33,12 @@ const SHADE = 0.15;                   // black, this alpha bottom-left -> transp
 // The mark, placed for the standalone master (bottom-right biased, full-bleed):
 const MASTER = { lh: 0.6055, lc: [0.4814, 0.4922], sd: 0.1729, sc: [0.7881, 0.7881] };
 // The mark, placed for the Android foreground layer (centred-ish inside the 61% safe
-// zone, nudged right 8% / down 3% for optical balance under the round mask; smaller ✻):
-const FOREGROUND = { lh: 0.5391, lc: [0.5234, 0.4951], sd: 0.1318, sc: [0.7627, 0.7266] };
+// zone, nudged right 8% / down 3% for optical balance under the round mask; smaller ✻).
+// Every value is the earlier placement scaled 0.75 about the icon centre (0.5, 0.5): the
+// whole mark is 25% smaller, its «Э»↔✻ arrangement unchanged, so the ✻ that used to graze
+// the round mask now sits well inside the safe zone. Round-mask launchers (adaptive + the
+// legacy round icon) get more breathing room; the full-bleed master is untouched.
+const FOREGROUND = { lh: 0.4043, lc: [0.5176, 0.4963], sd: 0.0989, sc: [0.6970, 0.6700] };
 
 const PALETTE = {
   light: { wood: '#e6b053', ink: '#5a3a12', grain: '#d8a54e' },