fix AWS S3 startup for production deployments

Pass S3_REGION and S3_PUBLIC_USE_SSL through compose, treat blank public
SSL as unset, and skip CreateBucket when IAM only allows access to an
existing bucket.

python/packages/server/src/officeconvert_server/config.py

@@ -31,10 +31,10 @@ class ServerConfig:
 def load_server_config() -> ServerConfig:
     """Load server configuration from environment variables."""
     s3_secure = os.getenv("S3_USE_SSL", "false").lower() == "true"
-    public_ssl_env = os.getenv("S3_PUBLIC_USE_SSL")
+    public_ssl_env = os.getenv("S3_PUBLIC_USE_SSL", "").strip()
     s3_public_secure = (
         public_ssl_env.lower() == "true"
-        if public_ssl_env is not None
+        if public_ssl_env
         else s3_secure
     )
     region_env = os.getenv("S3_REGION", "").strip()