feat: Integration Hub for external tool connectivity

- Add native config option: `new Brainy({ integrations: true })`
- OData integration for Excel Power Query and Power BI
- Google Sheets integration with Apps Script
- Server-Sent Events (SSE) for real-time streaming
- Webhooks for push notifications
- Zero-config with sensible defaults
- Full tree-shaking when disabled

integrations/google-sheets/appsscript.json

@@ -0,0 +1,11 @@
+{
+  "timeZone": "America/New_York",
+  "dependencies": {},
+  "exceptionLogging": "STACKDRIVER",
+  "runtimeVersion": "V8",
+  "oauthScopes": [
+    "https://www.googleapis.com/auth/spreadsheets.currentonly",
+    "https://www.googleapis.com/auth/script.container.ui",
+    "https://www.googleapis.com/auth/script.external_request"
+  ]
+}