feat(auth): implement Facebook identity binding on external entry

src/lib/navigation/external_entry.ts

@@ -3,6 +3,7 @@
 import { AuthStorage } from "@/data/storage/auth/auth_storage";
 import { UserStorage } from "@/data/storage/user/user_storage";
 import type { PendingChatPromotionType } from "@/data/storage/navigation";
+import type { LoginStatus } from "@/data/dto/auth";
 import { ROUTES } from "@/router/routes";
 
 export type ExternalEntryTarget =
@@ -26,6 +27,33 @@ export interface ExternalEntryPromotionInput {
   promotionType?: string | null;
 }
 
+export interface ExternalFacebookIdentityBindingInput {
+  hasInitialized: boolean;
+  isLoading: boolean;
+  loginStatus: LoginStatus;
+  asid?: string | null;
+  psid?: string | null;
+}
+
+export function shouldBindExternalFacebookIdentity({
+  hasInitialized,
+  isLoading,
+  loginStatus,
+  asid,
+  psid,
+}: ExternalFacebookIdentityBindingInput): boolean {
+  const isRealUser =
+    loginStatus === "email" ||
+    loginStatus === "google" ||
+    loginStatus === "facebook";
+  return (
+    hasInitialized &&
+    !isLoading &&
+    isRealUser &&
+    (hasValue(asid) || hasValue(psid))
+  );
+}
+
 export function resolveExternalEntryPromotionType({
   mode,
   promotionType,