Discord: add PluralKit sender identity resolver (#5838)

* Discord: add PluralKit sender identity resolver

* fix: resolve PluralKit sender identities (#5838) (thanks @thewilloftheshadow)

src/config/zod-schema.providers-core.ts

@@ -276,6 +276,13 @@ export const DiscordAccountSchema = z
       })
       .strict()
       .optional(),
+    pluralkit: z
+      .object({
+        enabled: z.boolean().optional(),
+        token: z.string().optional(),
+      })
+      .strict()
+      .optional(),
   })
   .strict();