fix: Fail early if deployment package size exceeds 250MB (#386)

* fix: agent_config.name bug when running configure after create with production template mode

* Early fail if deployment package exceeds 250MB

---------

Co-authored-by: Tejas Kashinath <tkashina@amazon.com>

Author: tejaskash

src/bedrock_agentcore_starter_toolkit/utils/runtime/package.py

@@ -217,7 +217,7 @@ def create_deployment_package(
             log.info("✓ Deployment package ready: %.2f MB", size_mb)
 
             if size_mb > 250:
-                log.warning("⚠️  Package size (%.2f MB) exceeds 250MB limit. Consider reducing dependencies.", size_mb)
+                raise Exception(f"Package size ({size_mb:.2f} MB) exceeds 250MB limit. Consider reducing dependencies.")
 
             # Check if aws-opentelemetry-distro is present for instrumentation
             has_otel_distro = self._check_otel_distro(requirements_file)