Remove api trigger kind and mark webhook as coming soon

Drop "api" from the trigger kind dropdown and disable the "webhook"
option with a "COMING SOON" label until it's ready.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/shared/src/validators/agent.ts

@@ -120,6 +120,7 @@ export type TestAdapterEnvironment = z.infer<typeof testAdapterEnvironmentSchema
 
 export const updateAgentPermissionsSchema = z.object({
   canCreateAgents: z.boolean(),
+  canAssignTasks: z.boolean(),
 });
 
 export type UpdateAgentPermissions = z.infer<typeof updateAgentPermissionsSchema>;