feat: Sprint 0 — project scaffold, DB schema, Zustand stores, base UI components

components/ui/Button.tsx

@@ -0,0 +1,37 @@
+import { TouchableOpacity, Text, ActivityIndicator } from 'react-native';
+
+interface ButtonProps {
+  label: string;
+  onPress: () => void;
+  variant?: 'primary' | 'secondary' | 'danger';
+  loading?: boolean;
+  disabled?: boolean;
+}
+
+export function Button({ label, onPress, variant = 'primary', loading, disabled }: ButtonProps) {
+  const base = 'rounded-xl py-4 px-6 items-center justify-center';
+  const variants = {
+    primary: 'bg-primary',
+    secondary: 'bg-secondary border border-primary',
+    danger: 'bg-danger',
+  };
+  const textColors = {
+    primary: 'text-white',
+    secondary: 'text-primary',
+    danger: 'text-white',
+  };
+
+  return (
+    <TouchableOpacity
+      className={`${base} ${variants[variant]} ${disabled || loading ? 'opacity-50' : ''}`}
+      onPress={onPress}
+      disabled={disabled || loading}
+    >
+      {loading ? (
+        <ActivityIndicator color={variant === 'secondary' ? '#1A6B72' : 'white'} />
+      ) : (
+        <Text className={`font-semibold text-base ${textColors[variant]}`}>{label}</Text>
+      )}
+    </TouchableOpacity>
+  );
+}