fix: Update MCP RAG classes to match BaseRAGExample signature

- Fix SlackMCPRAG and TwitterMCPRAG __init__ methods to provide required parameters
- Add name, description, and default_index_name to super().__init__ calls
- Resolves test failures: test_slack_rag_initialization and test_twitter_rag_initialization

This fixes the TypeError caused by BaseRAGExample requiring additional parameters.

apps/slack_rag.py

@@ -25,8 +25,11 @@ class SlackMCPRAG(BaseRAGExample):
     """
 
     def __init__(self):
-        super().__init__()
-        self.default_index_name = "slack_messages"
+        super().__init__(
+            name="Slack MCP RAG",
+            description="RAG application for Slack messages via MCP servers",
+            default_index_name="slack_messages"
+        )
 
     def _add_specific_arguments(self, parser: argparse.ArgumentParser):
         """Add Slack MCP-specific arguments."""

apps/twitter_rag.py

@@ -25,8 +25,11 @@ class TwitterMCPRAG(BaseRAGExample):
     """
 
     def __init__(self):
-        super().__init__()
-        self.default_index_name = "twitter_bookmarks"
+        super().__init__(
+            name="Twitter MCP RAG",
+            description="RAG application for Twitter bookmarks via MCP servers",
+            default_index_name="twitter_bookmarks"
+        )
 
     def _add_specific_arguments(self, parser: argparse.ArgumentParser):
         """Add Twitter MCP-specific arguments."""