Add document resource to n8n node and MCP sendSigningNotifications tool

Add a complete document resource to the n8n node with 21 operations
covering documents, versions, and signatures — matching the MCP
specification. Also add the sendSigningNotifications tool to the MCP
API for triggering pending signature reminders.

n8n operations: create, get, getAll, update, delete, archive,
unarchive, getVersion, getAllVersions, createDraftVersion,
updateVersion, deleteDraftVersion, publishMajorVersion,
publishMinorVersion, requestApproval, voidApproval, getSignature,
getAllSignatures, requestSignature, cancelSignature,
sendSigningNotifications.

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

pkg/server/api/mcp/v1/specification.yaml

@@ -5883,6 +5883,24 @@ components:
         document_version:
           $ref: "#/components/schemas/DocumentVersion"
 
+    SendSigningNotificationsInput:
+      type: object
+      required:
+        - organization_id
+      properties:
+        organization_id:
+          $ref: "#/components/schemas/GID"
+          description: Organization ID
+
+    SendSigningNotificationsOutput:
+      type: object
+      required:
+        - success
+      properties:
+        success:
+          type: boolean
+          description: Whether the notifications were sent successfully
+
     MeetingOrderField:
       type: string
       enum:
@@ -8515,6 +8533,14 @@ tools:
       $ref: "#/components/schemas/VoidDocumentVersionApprovalInput"
     outputSchema:
       $ref: "#/components/schemas/VoidDocumentVersionApprovalOutput"
+  - name: sendSigningNotifications
+    description: Send signing notifications to all signatories with pending signature requests in the organization
+    hints:
+      readonly: false
+    inputSchema:
+      $ref: "#/components/schemas/SendSigningNotificationsInput"
+    outputSchema:
+      $ref: "#/components/schemas/SendSigningNotificationsOutput"
   - name: listMeetings
     description: List all meetings for the organization
     hints: