fix: export Feature 051 API from common module

CRITICAL BUG FIX: v0.5.11 and v0.5.12 did not export the Feature 051 API
(get_iris_connection, detect_iris_edition, IRISConnectionPool) from the
common module's __init__.py file.

This caused ImportError for users trying to use the new simplified API:
  from iris_vector_rag.common import get_iris_connection  # Failed!

Files modified:
- iris_vector_rag/common/__init__.py: Added exports for Feature 051 API

Impact: This fixes the broken API in v0.5.11 and v0.5.12. Users can now
actually use the Feature 051 simplified connection API as documented.

Author: tom-dyar

iris_vector_rag/common/__init__.py

@@ -1 +1,14 @@
 # common module
+
+# Feature 051: Simplified IRIS Connection API
+from iris_vector_rag.common.iris_connection import (
+    get_iris_connection,
+    detect_iris_edition,
+    IRISConnectionPool,
+)
+
+__all__ = [
+    "get_iris_connection",
+    "detect_iris_edition",
+    "IRISConnectionPool",
+]