Redesign the UI after the fitness reference and replace the logo

Light sage-to-cream ambient backdrop, frosted glass controls and painted
SceneArt landscapes in place of photography. Home becomes a dashboard with a
two-tone greeting, a frosted summary ring, category portraits, an up-next rail
of image-led cards and a floating glass tab bar. The routine library gets an
image header and painted cards; the player gets a scene stage, steps on an
arc, a dotted clock and a night pill with a lime spark. Goals become painted
cards in their own colour.

New logo: a lime sun resting on a ground line under two arcs. The splash
raises the sun and lights the arcs; launcher icons and native splash are
regenerated to match.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KhQh614DMeYoQEH9SoMRUw

frontend/lib/Grounded/designs/AmbientBackground.dart

@@ -0,0 +1,61 @@
+import 'package:flutter/material.dart';
+
+import '../utils/Colors.dart';
+
+/// The airy backdrop: sage mist at the top drifting to cream, with two soft
+/// glows so the glass controls have something to blur.
+class AmbientBackground extends StatelessWidget {
+  final Widget child;
+
+  const AmbientBackground({super.key, required this.child});
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(
+      children: [
+        const Positioned.fill(
+          child: DecoratedBox(
+            decoration: BoxDecoration(
+              gradient: LinearGradient(
+                begin: Alignment.topCenter,
+                end: Alignment.bottomCenter,
+                colors: <Color>[
+                  colorAmbientTop,
+                  colorAmbientMid,
+                  colorAmbientBottom,
+                ],
+                stops: <double>[0.0, 0.45, 1.0],
+              ),
+            ),
+          ),
+        ),
+        Positioned(
+          top: -140,
+          right: -110,
+          child: _glow(380, colorAmbientGlowSage),
+        ),
+        Positioned(
+          top: 300,
+          left: -170,
+          child: _glow(360, colorAmbientGlowWarm),
+        ),
+        Positioned.fill(child: child),
+      ],
+    );
+  }
+
+  Widget _glow(double size, Color color) {
+    return IgnorePointer(
+      child: Container(
+        width: size,
+        height: size,
+        decoration: BoxDecoration(
+          shape: BoxShape.circle,
+          gradient: RadialGradient(
+            colors: <Color>[color, color.withValues(alpha: 0.0)],
+          ),
+        ),
+      ),
+    );
+  }
+}