feat(users): OTP delivery method picker on user creation + post-login agreement

Create User dialog now has a mandatory Email/Mobile OTP delivery method
picker (styled as a pill toggle) alongside the existing fields.

Adds a new post-login agreement acceptance dialog: right after the existing
2FA flow (TwoFactorAuthenticationComponent) succeeds, or immediately after
login for users without 2FA, the user must accept the bank's current
agreement/disclaimer at least once before reaching the app.

Also adds a "Manage User Agreement" admin screen (System section) to publish
versioned agreement text without a code deploy.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/login/login.component.html

@@ -247,13 +247,13 @@
       </div>
 
       <!-- Login Forms -->
-      @if (!resetPassword && !twoFactorAuthenticationRequired) {
+      @if (!resetPassword && !twoFactorAuthenticationRequired && !agreementAcceptanceRequired) {
         <mifosx-login-form></mifosx-login-form>
       }
       @if (resetPassword) {
         <mifosx-reset-password></mifosx-reset-password>
       }
-      <!-- 2FA opens as a non-dismissable dialog from login.component.ts -->
+      <!-- 2FA and the post-login agreement dialog open as non-dismissable dialogs from login.component.ts -->
 
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