fix: use correct env var syntax for Symfony secrets

Secrets are accessed via %env(NAME)% not %env(secret:NAME)%.
Symfony automatically resolves secrets as env vars.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

config/packages/flysystem.yaml

@@ -12,8 +12,8 @@ services:
         arguments:
             -   endpoint: 'https://s3.lclr.dev'
                 credentials:
-                    key: '%env(secret:S3_ACCESS_KEY)%'
+                    key: '%env(S3_ACCESS_KEY)%'
-                    secret: '%env(secret:S3_SECRET_KEY)%'
+                    secret: '%env(S3_SECRET_KEY)%'
                 region: 'us-east-1'
                 version: 'latest'
                 use_path_style_endpoint: true