feat: Add Loki MCP server scaffold, fix adapter blocking, upgrade model

- Scaffold mcp_servers/loki/ with config and async HTTP client
- Fix Slack/Telegram adapters to use non-blocking connections
- Upgrade default model to claude-sonnet-4-6
- Improve Agent SDK message collection for empty ResultMessage cases
- Add Message-ID to email summaries, increase body truncation limit
- Fix .gitignore inline comments that broke sensitive file exclusions

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

adapters/slack/adapter.py

@@ -88,7 +88,8 @@ class SlackAdapter(BaseAdapter):
         self.handler = AsyncSocketModeHandler(self.app, app_token)
 
         print("[Slack] Starting Socket Mode connection...")
-        await self.handler.start_async()
+        # Connect to Slack (non-blocking)
+        await self.handler.connect_async()
 
         self.is_running = True
         print("[Slack] Connected and listening for messages")
@@ -97,7 +98,7 @@ class SlackAdapter(BaseAdapter):
         """Stop the Slack Socket Mode connection."""
         if self.handler:
             print("[Slack] Stopping Socket Mode connection...")
-            await self.handler.close_async()
+            await self.handler.disconnect_async()
             self.is_running = False
             print("[Slack] Disconnected")