Step 2 (code quality): dedup + stop FE recomputing a server rule

- H1: tasksFromProfile takes the server's eligibleForHerregistratie decision
  instead of recomputing isHerregistratieEligible — the FE renders the rule,
  doesn't own it (ADR-0001). Policy reference impl kept for tests.
- M1: one shared runSubmit(fn, fallback) wrapper; the 4 submit-* commands keep
  only their payload mapping. +spec.
- M2: whenTag() kernel helper removes 10 repeated `as Extract<U,{tag}>` casts
  across the wizard/form components.

M4 (shared JA_NEE) folded into the upcoming i18n pass (clean dedup needs
$localize labels to sit in shared without breaking the English-shared-UI rule).
L1 already resolved by the restyle commit.

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

src/app/registratie/ui/dashboard.page.ts

@@ -1,4 +1,4 @@
-import { Component, inject } from '@angular/core';
+import { Component, computed, inject } from '@angular/core';
 import { PageShellComponent } from '@shared/layout/page-shell/page-shell.component';
 import { HeadingComponent } from '@shared/ui/heading/heading.component';
 import { LinkComponent } from '@shared/ui/link/link.component';
@@ -103,10 +103,15 @@ import { tasksFromProfile } from '@registratie/domain/tasks';
 })
 export class DashboardPage {
   protected store = inject(BigProfileStore);
-  private readonly today = new Date();
+
+  /** Server-computed eligibility (rendered, not recomputed). */
+  private readonly eligible = computed(() => {
+    const d = this.store.decisions();
+    return d.tag === 'Success' && d.value.eligibleForHerregistratie;
+  });
 
   protected tasksFor(reg: Registration) {
-    return tasksFromProfile(reg, this.today);
+    return tasksFromProfile(reg, this.eligible());
   }
 
   /** Portal sections (navigation, not actions). */