feat: add reusable PaginationLoader component with TDD

Add minimal PaginationLoader component for infinite scroll/pagination scenarios. Displays small ActivityIndicator with optional text, supports theme colors, and is designed for use in FlatList ListFooterComponent.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

components/PaginationLoader.test.tsx

@@ -0,0 +1,41 @@
+import React from 'react'
+import { render } from '@testing-library/react-native'
+import PaginationLoader from './PaginationLoader'
+
+describe('PaginationLoader Component', () => {
+  describe('Basic Rendering', () => {
+    it('should render ActivityIndicator', () => {
+      const { UNSAFE_root } = render(<PaginationLoader />)
+      expect(UNSAFE_root).toBeTruthy()
+    })
+
+    it('should render with optional text', () => {
+      const { getByText } = render(<PaginationLoader text="加载更多..." />)
+      expect(getByText('加载更多...')).toBeTruthy()
+    })
+
+    it('should render without text when not provided', () => {
+      const { queryByText } = render(<PaginationLoader />)
+      expect(queryByText(/./)).toBeNull()
+    })
+  })
+
+  describe('Theme Support', () => {
+    it('should use default color', () => {
+      const { UNSAFE_root } = render(<PaginationLoader />)
+      expect(UNSAFE_root).toBeTruthy()
+    })
+
+    it('should accept custom color', () => {
+      const { UNSAFE_root } = render(<PaginationLoader color="#FF0000" />)
+      expect(UNSAFE_root).toBeTruthy()
+    })
+  })
+
+  describe('Props', () => {
+    it('should accept testID prop', () => {
+      const { getByTestId } = render(<PaginationLoader testID="pagination-loader" />)
+      expect(getByTestId('pagination-loader')).toBeTruthy()
+    })
+  })
+})

components/PaginationLoader.tsx

@@ -0,0 +1,17 @@
+import React from 'react'
+import { View, ActivityIndicator, ViewProps } from 'react-native'
+import Text from './ui/Text'
+
+interface PaginationLoaderProps extends ViewProps {
+  text?: string
+  color?: string
+}
+
+export default function PaginationLoader({ text, color = '#F5F5F5', testID, ...props }: PaginationLoaderProps) {
+  return (
+    <View testID={testID} className="py-4 items-center" {...props}>
+      <ActivityIndicator size="small" color={color} />
+      {text && <Text className="mt-2 text-xs">{text}</Text>}
+    </View>
+  )
+}