Fix login output name collision and herregistratie demo eligibility

Walking through the running app surfaced two issues:

- login-form's `submit` output collided with the native DOM `submit` event
  bubbling to <app-login-form>, so login() also fired with an Event (not the
  BSN string) — "bsn.trim is not a function". Renamed the output to `submitted`
  (matching the other forms).
- The static mock herregistratie deadline (2027-09-01) sat outside the 12-month
  eligibility window, so the wizard was correctly hidden. Moved it to 2027-03-01
  so "verloopt binnenkort" is true and the flow is demoable.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/auth/ui/login-form/login-form.component.ts

@@ -9,7 +9,7 @@ import { ButtonComponent } from '@shared/ui/button/button.component';
   selector: 'app-login-form',
   imports: [FormsModule, FormFieldComponent, TextInputComponent, ButtonComponent],
   template: `
-    <form (ngSubmit)="submit.emit(bsn)">
+    <form (ngSubmit)="submitted.emit(bsn)">
       <app-form-field label="BSN" fieldId="bsn" description="9 cijfers (demo: vul iets in)">
         <app-text-input inputId="bsn" [(ngModel)]="bsn" name="bsn" placeholder="123456789" />
       </app-form-field>
@@ -27,5 +27,5 @@ import { ButtonComponent } from '@shared/ui/button/button.component';
 export class LoginFormComponent {
   bsn = '';
   password = '';
-  submit = output<string>();
+  submitted = output<string>();
 }

src/app/auth/ui/login.page.ts

@@ -12,7 +12,7 @@ import { SessionStore } from '@auth/application/session.store';
     <app-page-shell heading="Inloggen" width="narrow"
       intro="Log in op uw persoonlijke BIG-register omgeving.">
       @if (error()) { <app-alert type="error">{{ error() }}</app-alert> }
-      <app-login-form (submit)="login($event)" />
+      <app-login-form (submitted)="login($event)" />
     </app-page-shell>
   `,
 })