feat: Revamp card components and theme for Gen Z engagement with glassmorphism and enhanced UX

- Introduced advanced card components: GlassCard, ExpenseCard, GroupSummaryCard, and QuickActionCard.
- Enhanced GroupCard for backward compatibility with new design.
- Updated theme colors and typography to align with "Expressive Minimalism" and Gen Z preferences.
- Implemented glassmorphism effects and improved haptic feedback interactions.
- Refactored styles and animations for a cohesive user experience.

Author: Devasy

frontend/A Design Blueprint for a Modern, Minimalist Expens.md

@@ -0,0 +1,181 @@
+// Core Button Component - Following Blueprint Specifications
+// Implements the 8-second rule and haptic feedback for Gen Z engagement
+
+import * as Haptics from 'expo-haptics';
+import { LinearGradient } from 'expo-linear-gradient';
+import { ActivityIndicator, Text, TouchableOpacity, View } from 'react-native';
+import { borderRadius, colors, shadows, spacing } from '../../utils/theme';
+
+const Button = ({
+  title,
+  variant = 'primary', // primary, secondary, outline, ghost, destructive
+  size = 'medium', // small, medium, large
+  onPress,
+  disabled = false,
+  loading = false,
+  icon,
+  fullWidth = false,
+  style,
+  textStyle,
+  ...props
+}) => {
+  const handlePress = async () => {
+    if (disabled || loading) return;
+    
+    // Haptic feedback for engagement (Gen Z preference for tactile response)
+    await Haptics.impactAsync(Haptics.ImpactFeedbackStyle.Medium);
+    
+    if (onPress) {
+      onPress();
+    }
+  };
+
+  // Size configurations following minimum touch target of 44px
+  const sizeConfig = {
+    small: {
+      paddingVertical: spacing.sm,
+      paddingHorizontal: spacing.md,
+      minHeight: 36,
+      fontSize: 14,
+      fontWeight: '500',
+    },
+    medium: {
+      paddingVertical: spacing.md,
+      paddingHorizontal: spacing.lg,
+      minHeight: 44, // Accessibility minimum
+      fontSize: 16,
+      fontWeight: '600',
+    },
+    large: {
+      paddingVertical: spacing.lg,
+      paddingHorizontal: spacing.xl,
+      minHeight: 52,
+      fontSize: 18,
+      fontWeight: '600',
+    },
+  };
+
+  // Variant configurations for different button types
+  const variantConfig = {
+    primary: {
+      useGradient: true,
+      gradientColors: [colors.brand.accent, colors.brand.accentAlt],
+      textColor: '#FFFFFF',
+      shadowStyle: shadows.small,
+    },
+    secondary: {
+      backgroundColor: colors.background.secondary,
+      textColor: colors.text.primary,
+      borderWidth: 1,
+      borderColor: colors.border.subtle,
+      shadowStyle: shadows.subtle,
+    },
+    outline: {
+      backgroundColor: 'transparent',
+      textColor: colors.brand.accent,
+      borderWidth: 2,
+      borderColor: colors.brand.accent,
+    },
+    ghost: {
+      backgroundColor: 'transparent',
+      textColor: colors.brand.accent,
+    },
+    destructive: {
+      backgroundColor: colors.semantic.error,
+      textColor: '#FFFFFF',
+      shadowStyle: shadows.small,
+    },
+  };
+
+  const currentSize = sizeConfig[size];
+  const currentVariant = variantConfig[variant];
+
+  // Base button style
+  const buttonStyle = {
+    borderRadius: borderRadius.md,
+    alignItems: 'center',
+    justifyContent: 'center',
+    flexDirection: 'row',
+    minHeight: currentSize.minHeight,
+    paddingVertical: currentSize.paddingVertical,
+    paddingHorizontal: currentSize.paddingHorizontal,
+    width: fullWidth ? '100%' : 'auto',
+    opacity: disabled ? 0.6 : 1,
+    ...currentVariant.shadowStyle,
+    ...currentVariant,
+    ...style,
+  };
+
+  // Text style
+  const textStyleConfig = {
+    fontSize: currentSize.fontSize,
+    fontWeight: currentSize.fontWeight,
+    color: currentVariant.textColor,
+    fontFamily: 'Inter',
+    ...textStyle,
+  };
+
+  // Loading spinner color
+  const spinnerColor = currentVariant.textColor;
+
+  const ButtonContent = () => (
+    <View style={{ flexDirection: 'row', alignItems: 'center' }}>
+      {loading && (
+        <ActivityIndicator 
+          size="small" 
+          color={spinnerColor} 
+          style={{ marginRight: spacing.sm }} 
+        />
+      )}
+      {icon && !loading && (
+        <View style={{ marginRight: spacing.sm }}>
+          {icon}
+        </View>
+      )}
+      <Text style={textStyleConfig}>
+        {title}
+      </Text>
+    </View>
+  );
+
+  // Render with gradient if specified
+  if (currentVariant.useGradient && !disabled) {
+    return (
+      <TouchableOpacity
+        onPress={handlePress}
+        disabled={disabled || loading}
+        activeOpacity={0.8}
+        style={[buttonStyle, { backgroundColor: 'transparent' }]}
+        {...props}
+      >
+        <LinearGradient
+          colors={currentVariant.gradientColors}
+          style={{
+            ...buttonStyle,
+            shadowColor: 'transparent', // Remove shadow from gradient container
+            elevation: 0,
+          }}
+          start={{ x: 0, y: 0 }}
+          end={{ x: 1, y: 0 }}
+        >
+          <ButtonContent />
+        </LinearGradient>
+      </TouchableOpacity>
+    );
+  }
+
+  // Regular button without gradient
+  return (
+    <TouchableOpacity
+      onPress={handlePress}
+      disabled={disabled || loading}
+      activeOpacity={0.8}
+      style={buttonStyle}
+      {...props}
+    >
+      <ButtonContent />
+    </TouchableOpacity>
+  );
+};
+
+export default Button;