Add S3/MinIO storage for deployment previews

- Add S3 client helper (src/lib/s3.ts) with upload/download functions
- Add /api/deployments/[uuid]/preview endpoint for presigned URLs
- Update DeploymentDashboard to fetch and display preview images
- Install @aws-sdk/client-s3 and @aws-sdk/s3-request-presigner

Storage: MinIO bucket nuc-portal-previews with dedicated service account

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

src/app/api/deployments/[uuid]/preview/route.ts

@@ -0,0 +1,54 @@
+import { NextResponse } from 'next/server';
+import { getPreviewUrl, previewExists } from '@/lib/s3';
+import { fetchDeploymentDetail } from '@/lib/coolify-db';
+
+export async function GET(
+  _request: Request,
+  { params }: { params: Promise<{ uuid: string }> }
+) {
+  const { uuid } = await params;
+
+  try {
+    // Get deployment to find application UUID
+    const deployment = await fetchDeploymentDetail(uuid);
+
+    if (!deployment) {
+      return NextResponse.json({ error: 'Deployment not found' }, { status: 404 });
+    }
+
+    const appUuid = deployment.application_uuid;
+
+    // Check if preview exists
+    const exists = await previewExists(appUuid, uuid);
+
+    if (!exists) {
+      return NextResponse.json({
+        exists: false,
+        message: 'Preview not available',
+        hint: 'Screenshot will be captured after successful deployment',
+      });
+    }
+
+    // Get presigned URL (valid for 1 hour)
+    const url = await getPreviewUrl(appUuid, uuid);
+
+    if (!url) {
+      return NextResponse.json(
+        { error: 'Failed to generate preview URL' },
+        { status: 500 }
+      );
+    }
+
+    return NextResponse.json({
+      exists: true,
+      url,
+      expiresIn: 3600,
+    });
+  } catch (error) {
+    console.error('Preview fetch error:', error);
+    return NextResponse.json(
+      { error: 'Failed to fetch preview', details: String(error) },
+      { status: 500 }
+    );
+  }
+}