Mobile: redesign, onboarding, QR codes, logo, Spotify setup

- Redesign matching the web: album-art backdrops, Reanimated equalizer,
  spinning live ring, drifting ambient background, gradient buttons with
  spring press feedback and haptics, Space Grotesk headings, animated feed
  (enter + layout transitions); fix invisible tab labels
- Four-step onboarding for new accounts: which app you listen with (sets
  where songs open), the matching share setup, find friends (search,
  scan, invite), and a featured song. Skippable; stored server-side
- QR codes: My code (share link) and an in-app scanner (camera only, no
  microphone permission)
- Spotify setup via Last.fm or ListenBrainz with guided linking; Android
  shares Spotify automatically through the phone reader
- New logo as app icon, adaptive/monochrome icon and splash
- app.config.ts allows cleartext only for local http:// test builds

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/mobile/src/components/AmbientBackground.tsx

@@ -0,0 +1,36 @@
+import { Image } from 'expo-image';
+import { useEffect } from 'react';
+import { StyleSheet, useWindowDimensions, View } from 'react-native';
+import Animated, { Easing, useAnimatedStyle, useSharedValue, withRepeat, withTiming } from 'react-native-reanimated';
+import { colors } from '@/lib/theme';
+
+const AnimatedImage = Animated.createAnimatedComponent(Image);
+
+/** Two soft colour blobs drifting slowly behind the content, so screens never feel static. */
+export function AmbientBackground() {
+  const { width, height } = useWindowDimensions();
+  const t = useSharedValue(0);
+
+  useEffect(() => {
+    t.set(withRepeat(withTiming(1, { duration: 18000, easing: Easing.inOut(Easing.sin) }), -1, true));
+  }, [t]);
+
+  const size = Math.max(width, height) * 0.9;
+  const purple = useAnimatedStyle(() => ({
+    transform: [{ translateX: -size * 0.35 + t.value * width * 0.35 }, { translateY: -size * 0.3 + t.value * height * 0.12 }],
+  }));
+  const blue = useAnimatedStyle(() => ({
+    transform: [{ translateX: width - size * 0.6 - t.value * width * 0.3 }, { translateY: height - size * 0.55 - t.value * height * 0.1 }],
+  }));
+
+  return (
+    <View style={[StyleSheet.absoluteFill, { backgroundColor: colors.bg }]} pointerEvents="none">
+      <AnimatedImage source={require('@/assets/images/ambient-purple.png')} style={[styles.blob, { width: size, height: size }, purple]} />
+      <AnimatedImage source={require('@/assets/images/ambient-blue.png')} style={[styles.blob, { width: size, height: size }, blue]} />
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  blob: { position: 'absolute', top: 0, left: 0, opacity: 0.45 },
+});