PM-2684: add member-api fallback for invite email resolution

What was broken

- Invite email target resolution depended only on Identity API email lookups.

- When those lookups failed, existing Topcoder members invited by email were treated as non-members and routed through the registration-template path.

Root cause

-  had no fallback source for unresolved emails and silently returned no user matches.

What was changed

- Updated  to keep Identity API as primary lookup and fallback unresolved emails to Member API email search ().

- Mapped Member API  records into  shape and deduplicated merged results.

- Added safe primitive-string normalization helpers used during response parsing.

Any added/updated tests

- Added  with coverage for Identity API success and Member API fallback paths.

Author: jmgasper

src/shared/services/identity.service.spec.ts

@@ -0,0 +1,139 @@
+import { HttpService } from '@nestjs/axios';
+import { of, throwError } from 'rxjs';
+import { M2MService } from 'src/shared/modules/global/m2m.service';
+import { IdentityService } from './identity.service';
+
+jest.mock('src/shared/config/service-endpoints.config', () => ({
+  SERVICE_ENDPOINTS: {
+    identityApiUrl: 'https://identity.test',
+    memberApiUrl: 'https://member.test',
+  },
+}));
+
+describe('IdentityService', () => {
+  const httpServiceMock = {
+    get: jest.fn(),
+  };
+
+  const m2mServiceMock = {
+    getM2MToken: jest.fn().mockResolvedValue('m2m-token'),
+  };
+
+  let service: IdentityService;
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+
+    service = new IdentityService(
+      httpServiceMock as unknown as HttpService,
+      m2mServiceMock as unknown as M2MService,
+    );
+  });
+
+  it('returns users from Identity API when lookups succeed', async () => {
+    httpServiceMock.get.mockImplementation(
+      (url: string, options: { params?: { filter?: string } }) => {
+        if (
+          url === 'https://identity.test/users' &&
+          options.params?.filter === 'email=member1@topcoder.com'
+        ) {
+          return of({
+            data: [
+              {
+                id: '1001',
+                handle: 'member1',
+                email: 'member1@topcoder.com',
+              },
+            ],
+          });
+        }
+
+        if (
+          url === 'https://identity.test/users' &&
+          options.params?.filter === 'email=member2@topcoder.com'
+        ) {
+          return of({
+            data: [
+              {
+                id: '1002',
+                handle: 'member2',
+                email: 'member2@topcoder.com',
+              },
+            ],
+          });
+        }
+
+        return of({ data: [] });
+      },
+    );
+
+    const result = await service.lookupMultipleUserEmails([
+      'member1@topcoder.com',
+      'member2@topcoder.com',
+    ]);
+
+    expect(result).toEqual([
+      {
+        id: '1001',
+        handle: 'member1',
+        email: 'member1@topcoder.com',
+      },
+      {
+        id: '1002',
+        handle: 'member2',
+        email: 'member2@topcoder.com',
+      },
+    ]);
+
+    expect(m2mServiceMock.getM2MToken).toHaveBeenCalledTimes(1);
+  });
+
+  it('falls back to Member API for unresolved emails', async () => {
+    httpServiceMock.get.mockImplementation(
+      (url: string, options: { params?: { email?: string } }) => {
+        if (url === 'https://identity.test/users') {
+          return throwError(() => new Error('identity lookup failed'));
+        }
+
+        if (
+          url === 'https://member.test' &&
+          options.params?.email === 'existing@topcoder.com'
+        ) {
+          return of({
+            data: [
+              {
+                userId: 2001,
+                handle: 'existing',
+                email: 'existing@topcoder.com',
+              },
+            ],
+          });
+        }
+
+        if (
+          url === 'https://member.test' &&
+          options.params?.email === 'newuser@topcoder.com'
+        ) {
+          return of({ data: [] });
+        }
+
+        return of({ data: [] });
+      },
+    );
+
+    const result = await service.lookupMultipleUserEmails([
+      'existing@topcoder.com',
+      'newuser@topcoder.com',
+    ]);
+
+    expect(result).toEqual([
+      {
+        id: '2001',
+        handle: 'existing',
+        email: 'existing@topcoder.com',
+      },
+    ]);
+
+    expect(m2mServiceMock.getM2MToken).toHaveBeenCalledTimes(1);
+  });
+});