Revert to simple environment variable approach

- Remove backend pipeline deployment that was causing IAM issues
- Remove complex secret configuration from backend.ts
- Use simple environment variable approach from Amplify Console

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

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

amplify.yml

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

amplify/backend.ts

@@ -1,18 +1,11 @@
-import { defineBackend, secret } from '@aws-amplify/backend';
+import { defineBackend } from '@aws-amplify/backend';
 import { auth } from './auth/resource';
 import { data } from './data/resource';
 
 /**
  * @see https://docs.amplify.aws/react/build-a-backend/ to add storage, functions, and more
  */
-const backend = defineBackend({
+defineBackend({
   auth,
   data,
 });
-
-// Define secrets that will be available as environment variables
-backend.addOutput({
-  custom: {
-    YOUTUBE_API_KEY: secret('YOUTUBE_API_KEY'),
-  },
-});