fix: allow deployment bundle validation

infra/cdk/README.md

@@ -41,8 +41,10 @@ The role grants only:
 - `elasticbeanstalk:CreateApplicationVersion` on application `shoc-backend`.
 - `elasticbeanstalk:UpdateEnvironment` on environment `shoc-backend-dev` only.
 - `s3:ListBucket` on `elasticbeanstalk-us-east-1-396287094661` (the official
-  action's ownership-safe `HeadBucket` check) and `s3:PutObject` only under the
-  `shoc-backend/` object prefix.
+  action's ownership-safe `HeadBucket` check). Under the `shoc-backend/` object
+  prefix only: `s3:PutObject` plus `s3:GetObject` and `s3:GetObjectVersion`,
+  which the pinned official deployment action requires to validate the
+  `CreateApplicationVersion` source bundle after upload.
 
 It grants **no** IAM mutation or `PassRole`, **no** RDS / EC2 / Secrets Manager
 access, and **no** administrator policy. There are no wildcard mutation

infra/cdk/deploy-dev-stack.ts

@@ -81,7 +81,7 @@ export class DeployDevStack extends cdk.Stack {
     deployRole.addToPolicy(
       new iam.PolicyStatement({
         effect: iam.Effect.ALLOW,
-        actions: ['s3:PutObject'],
+        actions: ['s3:GetObject', 's3:GetObjectVersion', 's3:PutObject'],
         resources: [`${bucketArn}/${APPLICATION_NAME}/*`],
       }),
     );