Make isAgentEmail case-insensitive

Add the `i` flag to AGENT_EMAIL_REGEX so inputs like
AGENT_123@EXPENSIFY.AI are also blocked. Add a test case
for mixed-case agent emails.

Co-authored-by: Nicolás Bonet <NicolasBonet@users.noreply.github.com>

Author: MelvinBot

src/libs/SessionUtils.ts

@@ -108,7 +108,7 @@ function checkIfShouldUseNewPartnerName(partnerUserID?: string): boolean {
     return false;
 }
 
-const AGENT_EMAIL_REGEX = /^agent_\d+@expensify\.ai$/;
+const AGENT_EMAIL_REGEX = /^agent_\d+@expensify\.ai$/i;
 
 function isAgentEmail(email?: string): boolean {
     if (!email) {

tests/ui/BaseLoginFormTest.tsx

@@ -104,6 +104,21 @@ describe('BaseLoginForm', () => {
         expect(mockBeginSignIn).not.toHaveBeenCalled();
     });
 
+    it('blocks agent email regardless of case', async () => {
+        renderForm();
+
+        const input = screen.getByTestId('username');
+        fireEvent.changeText(input, 'AGENT_123@EXPENSIFY.AI');
+
+        const continueButton = screen.getByText('Continue');
+        fireEvent.press(continueButton);
+
+        await waitFor(() => {
+            expect(screen.getByText(AGENT_ERROR)).toBeTruthy();
+        });
+        expect(mockBeginSignIn).not.toHaveBeenCalled();
+    });
+
     it('proceeds with sign-in for a normal email', async () => {
         renderForm();