Implement proper Amplify Gen 2 secret management

- Create Lambda function with secret environment variable
- Add YouTube API function to backend configuration
- Create Next.js API route to handle YouTube requests
- Update gallery page to use API route
- This follows the correct Amplify Gen 2 pattern for secrets

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

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

amplify.yml

@@ -1,4 +1,10 @@
 version: 1
+backend:
+  phases:
+    build:
+      commands:
+        - npm ci
+        - npx ampx pipeline-deploy --branch $AWS_BRANCH --app-id $AWS_APP_ID
 frontend:
   phases:
     preBuild: