feat: Serverless Functions as AI Tools (#16919)

## Summary

This PR enables serverless functions to be exposed as AI tools, allowing
them to be used by AI agents.

### Changes

- Added new `SERVERLESS_FUNCTION` tool category
- Added `toolDescription`, `toolInputSchema`, and `toolOutputSchema`
fields to serverless functions
- Created database migration for the new schema columns
- Added tool index query and resolver for fetching available tools
- Added Settings AI page tabs (Skills, Tools, Settings) with new tools
table
- Added utility to convert tool schema to JSON schema format
- Updated frontend to display tools in the settings page

### Implementation Details

- Serverless functions can now define tool metadata (description,
input/output schemas)
- These functions are automatically registered in the tool registry
- The tool index endpoint allows querying available tools with their
schemas
- Settings page now has a dedicated Tools tab showing all available
tools

packages/twenty-server/src/engine/metadata-modules/flat-entity/constant/all-flat-entity-properties-to-compare-and-stringify.constant.ts

@@ -80,7 +80,7 @@ export const ALL_FLAT_ENTITY_PROPERTIES_TO_COMPARE_AND_STRINGIFY = {
       ),
       'deletedAt',
     ],
-    propertiesToStringify: [],
+    propertiesToStringify: ['toolInputSchema'],
   },
   cronTrigger: {
     propertiesToCompare: [...FLAT_CRON_TRIGGER_EDITABLE_PROPERTIES],