fix: 修复表单相册上传失败bug，优化FormData构造方式

- 移除uploadFile.ts中不必要的Platform判断逻辑
- 保持原始URI不做修改，让React Native底层处理平台差异
- 添加uploadFile单元测试，覆盖主要上传场景
- 简化代码结构，提高可维护性

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

app/(tabs)/__tests__/index.test.tsx

@@ -1,8 +1,14 @@
 import React from 'react'
 import { render, waitFor } from '@testing-library/react-native'
-import { SafeAreaProvider } from 'react-native-safe-area-context'
 import HomeScreen from '../index'
 
+// Mock react-native-safe-area-context FIRST
+jest.mock('react-native-safe-area-context', () => ({
+    SafeAreaProvider: ({ children }: any) => children,
+    SafeAreaView: ({ children }: any) => children,
+    useSafeAreaInsets: () => ({ top: 0, right: 0, bottom: 0, left: 0 }),
+}))
+
 // Mock expo-linear-gradient
 jest.mock('expo-linear-gradient', () => ({
     LinearGradient: 'LinearGradient',
@@ -94,15 +100,16 @@ jest.mock('@/hooks/use-categories', () => ({
     })),
 }))
 
+jest.mock('@/hooks/use-user-balance', () => ({
+    useUserBalance: jest.fn(() => ({
+        balance: 1234,
+        loading: false,
+        error: null,
+    })),
+}))
+
 const renderWithProviders = (component: React.ReactElement) => {
-    return render(
-        <SafeAreaProvider initialMetrics={{
-            frame: { x: 0, y: 0, width: 375, height: 812 },
-            insets: { top: 44, left: 0, right: 0, bottom: 34 },
-        }}>
-            {component}
-        </SafeAreaProvider>
-    )
+    return render(component)
 }
 
 describe('HomeScreen', () => {
@@ -137,4 +144,12 @@ describe('HomeScreen', () => {
             expect(queryByText('加载中')).toBeNull()
         })
     })
+
+    it('should display user balance from useUserBalance hook', async () => {
+        const { getByText } = renderWithProviders(<HomeScreen />)
+
+        await waitFor(() => {
+            expect(getByText('1234')).toBeTruthy()
+        })
+    })
 })