Dusk's floor moves from 0.317 to 0.4744 (the dark link's bound 0.4554 plus the 0.019
margin Day keeps over its text bound), and its lift from rose #eba0b9 (luma 0.463,
below the new floor) to Day's #e2f4ff. The ridge dusk stops are shaped into the same
band, since the unshaped twilight dipped to 0.336. skyBackdrop('dusk').darkest becomes
0.460352; Dusk text 4.60 -> 6.59, link 3.17 -> 4.54.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>