Remove link property from booking_history_entry schema

The link field exposed internal admin paths and payment dashboard URLs.
Remove it from the public API schema.

https://claude.ai/code/session_014Bxd8mJrp72PwiwM3tWGqm

Author: claude

v2/jammed.yaml

@@ -2808,10 +2808,6 @@ components:
           type: string
           nullable: true
           description: Detailed description of the event
-        link:
-          type: string
-          nullable: true
-          description: Related URL for the event
       required:
       - title
       - timestamp