design: bring back the Camogli harbor backdrop in v2

Body uses the harbor as a fixed full-page photo with brightness 0.42 +
the theme's color overlay at 0.72 opacity (multiply blend) for the dusk
tint. Applies via the shared wevisto-design.css so both Twig pages and
the SPA get it in one go.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

public/css/wevisto-design.css

@@ -93,16 +93,34 @@
   --color-secondary: #3a2c1a;
 }
 
-/* ─── v2 base body — solid navy with subtle gradient, no full-page photo
+/* ─── v2 base body — Camogli harbor backdrop with theme-tinted overlay
  * Applies to BOTH Twig pages and the SPA. Component styles live elsewhere.
  */
 [data-design="v2"] body {
-  background:
-    radial-gradient(ellipse 90% 70% at 50% 30%,
-      color-mix(in srgb, var(--color-surface-2) 80%, transparent) 0%,
-      transparent 70%),
-    var(--color-bg);
   color: var(--color-text);
+  background: var(--color-bg);
+  position: relative;
+  min-height: 100dvh;
+}
+[data-design="v2"] body::before {
+  content: '';
+  position: fixed;
+  inset: 0;
+  background: url('/build/assets/harbor.jpg') center/cover no-repeat;
+  filter: brightness(0.42) saturate(0.85);
+  z-index: -3;
+}
+[data-design="v2"] body::after {
+  content: '';
+  position: fixed;
+  inset: 0;
+  background:
+    radial-gradient(ellipse 80% 70% at 50% 50%, transparent 0%, rgba(0,0,0,0.45) 100%),
+    var(--color-bg);
+  opacity: 0.72;
+  mix-blend-mode: multiply;
+  z-index: -2;
+  pointer-events: none;
 }
 
 /* ─── v2 typography defaults — h1/h2/h3 become editorial display ──── */