✨ feat: 完整的生成流程 - 登录检查、文件上传、支付凭证验证

主要功能：
1. ✅ 添加 canGenerate() - 检查登录、metered 订阅、余额
2. ✅ 添加 uploadBlobFiles() - 自动上传所有 blob URL 到服务器
3. ✅ 支付凭证强制验证 - identifier 缺失时报错"支付失败"
4. ✅ 新增 lib/api/upload.ts - 文件上传 API
5. ✅ 更新 useTemplateRun hook 支持 identifier 参数

完整流程（7步骤）：
  1. 表单验证
  2. canGenerate 检查（登录 + 订阅 + 余额）
  3. 上传 blob 文件到服务器
  4. recordTokenUsage 扣费并获取 identifier
  5. 验证所有 URL 都是服务器 URL
  6. 转换数据格式
  7. runTemplate(id, data, identifier) 创建任务

安全保障：
- ❌ 无 identifier → 抛出错误"支付凭证缺失"
- ❌ blob URL 未上传 → 报错"存在未上传的文件"
- ❌ 余额不足 → 引导用户充值

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/templates/[id]/form.tsx

@@ -20,9 +20,11 @@ export const unstable_settings = {
 import { BackButton } from '@/components/ui/back-button';
 import { DynamicFormField } from '@/components/forms/dynamic-form-field';
 import { getTemplateById } from '@/lib/api/templates';
-import { recordTokenUsage } from '@/lib/api/balance';
+import { recordTokenUsage, getUserBalance } from '@/lib/api/balance';
 import { runTemplate } from '@/lib/api/template-runs';
+import { uploadFile } from '@/lib/api/upload';
 import { Template, TemplateGraphNode } from '@/lib/types/template';
+import { useAuth } from '@/hooks/use-auth';
 
 const FALLBACK_PREVIEW =
   'https://images.unsplash.com/photo-1542204165-0198c1e21a3b?auto=format&fit=crop&w=1200&q=80';
@@ -32,6 +34,7 @@ const FALLBACK_INSET =
 export default function TemplateFormScreen() {
   const { id } = useLocalSearchParams<{ id: string }>();
   const router = useRouter();
+  const { session, isLoading: authLoading } = useAuth();
 
   const [template, setTemplate] = useState<Template | null>(null);
   const [loading, setLoading] = useState(true);
@@ -95,6 +98,73 @@ export default function TemplateFormScreen() {
     return Object.keys(newErrors).length === 0;
   };
 
+  /**
+   * 检查用户是否可以生成（登录 + metered 订阅 + 余额充足）
+   */
+  const canGenerate = async (): Promise<{ canProceed: boolean; message?: string }> => {
+    // 1. 检查是否登录
+    if (!session?.user) {
+      return {
+        canProceed: false,
+        message: '请先登录',
+      };
+    }
+
+    // 2. 检查是否有 metered 订阅
+    const balanceResponse = await getUserBalance();
+    if (!balanceResponse.success) {
+      return {
+        canProceed: false,
+        message: balanceResponse.message || '未找到计费订阅，请先订阅',
+      };
+    }
+
+    // 3. 检查余额是否充足
+    const requiredAmount = template?.costPrice || 0;
+    const currentBalance = balanceResponse.data.remainingTokenBalance;
+
+    if (currentBalance < requiredAmount) {
+      return {
+        canProceed: false,
+        message: `余额不足\n当前余额: ${currentBalance}\n需要费用: ${requiredAmount}`,
+      };
+    }
+
+    return { canProceed: true };
+  };
+
+  /**
+   * 上传所有 blob URL 文件到服务器
+   */
+  const uploadBlobFiles = async (data: Record<string, any>): Promise<Record<string, any>> => {
+    if (!template?.formSchema?.startNodes) return data;
+
+    const uploadedData = { ...data };
+
+    for (const node of template.formSchema.startNodes) {
+      const value = data[node.id];
+
+      if (!value) continue;
+
+      // 检查是否是 blob URL
+      if (typeof value === 'string' && value.startsWith('blob:')) {
+        const fileType = node.type === 'image' ? 'image' : node.type === 'video' ? 'video' : null;
+
+        if (fileType) {
+          const uploadResponse = await uploadFile(value, fileType as 'image' | 'video');
+
+          if (!uploadResponse.success || !uploadResponse.data) {
+            throw new Error(`上传 ${node.data.label} 失败`);
+          }
+
+          uploadedData[node.id] = uploadResponse.data.url;
+        }
+      }
+    }
+
+    return uploadedData;
+  };
+
   const transformFormDataToRunFormat = (formData: Record<string, any>): Record<string, any> => {
     if (!template?.formSchema?.startNodes) return {};
 
@@ -161,7 +231,29 @@ export default function TemplateFormScreen() {
     setIsSubmitting(true);
 
     try {
-      // 1. 扣费（已集成余额检查和错误处理）
+      // 步骤 1: 检查是否可以生成（登录 + 订阅 + 余额）
+      const checkResult = await canGenerate();
+      if (!checkResult.canProceed) {
+        Alert.alert('无法生成', checkResult.message || '请检查账户状态', [
+          { text: '取消', style: 'cancel' },
+          {
+            text: '去充值',
+            onPress: () => router.push('/exchange' as any),
+          },
+        ]);
+        return;
+      }
+
+      // 步骤 2: 上传所有 blob 文件到服务器
+      let uploadedFormData: Record<string, any>;
+      try {
+        uploadedFormData = await uploadBlobFiles(formData);
+      } catch (uploadError) {
+        Alert.alert('上传失败', uploadError instanceof Error ? uploadError.message : '文件上传失败，请重试');
+        return;
+      }
+
+      // 步骤 3: 扣费并获取 identifier
       const requiredAmount = template.costPrice || 0;
       const usageResponse = await recordTokenUsage({
         price: requiredAmount,
@@ -172,16 +264,28 @@ export default function TemplateFormScreen() {
         },
       });
 
-      if (!usageResponse.success) {
-        // recordTokenUsage 已经显示了错误提示，这里不需要重复
+      if (!usageResponse.success || !usageResponse.data?.identifier) {
+        Alert.alert('扣费失败', usageResponse.message || '请稍后重试');
         return;
       }
 
-      // 2. 转换表单数据为正确的 API 格式
-      const transformedData = transformFormDataToRunFormat(formData);
+      const paymentIdentifier = usageResponse.data.identifier;
 
-      // 3. 调用 template run
-      const runResponse = await runTemplate(id, transformedData);
+      // 步骤 4: 验证所有 URL 都是有效的服务器 URL
+      const hasInvalidUrl = Object.values(uploadedFormData).some(
+        (value) => typeof value === 'string' && value.startsWith('blob:')
+      );
+
+      if (hasInvalidUrl) {
+        Alert.alert('错误', '存在未上传的文件，请重试');
+        return;
+      }
+
+      // 步骤 5: 转换表单数据为 API 格式
+      const transformedData = transformFormDataToRunFormat(uploadedFormData);
+
+      // 步骤 6: 调用 template run，使用支付凭证 identifier
+      const runResponse = await runTemplate(id, transformedData, paymentIdentifier);
 
       if (!runResponse.success) {
         Alert.alert('错误', '生成任务创建失败');
@@ -190,7 +294,7 @@ export default function TemplateFormScreen() {
 
       const generationId = runResponse.data;
 
-      // 4. 跳转到结果页面
+      // 步骤 7: 跳转到结果页面
       Alert.alert('成功', '视频生成任务已创建', [
         {
           text: '查看结果',