REFACTOR(repo): simplify project structure

- Move services/nextjs to nextjs/
- Move deploy/docker/Dockerfile.prod to Dockerfile
- Add GitHub Actions workflows (ci.yml, build.yml)
- Remove deploy/, services/, scripts/ folders

nextjs/app/api/upload-url/route.ts

@@ -0,0 +1,57 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { PutObjectCommand } from '@aws-sdk/client-s3';
+import { getSignedUrl } from '@aws-sdk/s3-request-presigner';
+import { S3_CONFIG, s3Client } from '@/shared/config/s3';
+
+// 파일 업로드 URL 생성
+const generateUploadUrl = async (
+  fileName: string,
+  fileType: string,
+  folder?: string
+): Promise<{ uploadUrl: string; fileKey: string }> => {
+  try {
+    const fileKey = folder ? `${folder}/${Date.now()}-${fileName}` : `${Date.now()}-${fileName}`;
+    
+    const command = new PutObjectCommand({
+      Bucket: S3_CONFIG.BUCKET_NAME,
+      Key: fileKey,
+      ContentType: fileType,
+    });
+
+    const uploadUrl = await getSignedUrl(s3Client, command, { expiresIn: 3600 });
+
+    return {
+      uploadUrl,
+      fileKey,
+    };
+  } catch (error: any) {
+    throw new Error(`업로드 URL 생성에 실패했습니다: ${error.message}`);
+  }
+};
+
+export async function POST(request: NextRequest) {
+  try {
+    const body = await request.json();
+    const { fileName, fileType, folder } = body;
+
+    if (!fileName || !fileType) {
+      return NextResponse.json(
+        { error: 'fileName과 fileType이 필요합니다.' },
+        { status: 400 }
+      );
+    }
+
+    const { uploadUrl, fileKey } = await generateUploadUrl(fileName, fileType, folder || 'jotion-uploads');
+
+    return NextResponse.json({
+      uploadUrl,
+      fileKey,
+    });
+  } catch (error: any) {
+    return NextResponse.json(
+      { error: error.message || '업로드 URL 생성에 실패했습니다.' },
+      { status: 500 }
+    );
+  }
+}
+