dev_fix: update __init__.py to set environment variable for Google GenAI SDK to use Vertex AI

rag_agent/__init__.py

@@ -1 +1,10 @@
-from . import agent
+"""Package export for the ADK root agent."""
+
+import os
+
+# Ensure the Google GenAI SDK talks to Vertex AI instead of the public Gemini API.
+os.environ.setdefault("GOOGLE_GENAI_USE_VERTEXAI", "true")
+
+from .agent import root_agent
+
+__all__ = ["root_agent"]