style(home): lift the hero artwork's dark-theme brightness to 0.75

At 0.52 the scene was legible but heavily suppressed; 0.75 lets the hills,
path and schoolhouse read while the white H1 stays comfortably the brightest
thing on the panel.

Re-measured rather than assumed, because in the dark theme the text is light
and the artwork is behind it — brightening the image lowers text contrast
rather than raising it. Off rendered pixels, sampling background up to 120px
past each line's right edge:

  brightness   title      body
  0.52         11.01:1    6.44:1
  0.75          9.48:1    5.21:1

Both still clear the 4.5:1 floor, body being the binding one. The trade is
recorded next to the value so the next person to reach for it knows it has a
floor and not just a taste range.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

nextjs-app/components/HomeView.module.css

@@ -161,10 +161,22 @@
  * page and out-shouts the H1 and the search box. Dimming it in CSS is the
  * whole treatment, and the scrim then fades it into the dark panel instead of
  * into cream.
+ *
+ * Raising the brightness raises the background under light dark-theme text, so
+ * this value has a contrast floor, not just a taste range. Measured off
+ * rendered pixels, sampling background up to 120px past each line:
+ *
+ *   brightness   title      body
+ *   0.52         11.01:1    6.44:1
+ *   0.75          9.48:1    5.21:1   ← current
+ *
+ * Body text is the binding one. Going much above 0.75 walks it toward the
+ * 4.5:1 floor, and at that point the scrim needs to carry further right rather
+ * than the artwork being dimmed less.
  */
 @media (prefers-color-scheme: dark) {
   .heroArt img {
-    filter: brightness(0.52) saturate(0.72) contrast(1.02);
+    filter: brightness(0.75) saturate(0.72) contrast(1.02);
   }
   .heroPanel::before {
     background: linear-gradient(