feat(backend): enforce the scholing threshold server-side (WP-69)

ADR-0001's own canonical "config value" example was unenforced: GET
/intake/policy echoed ScholingThreshold, but no request DTO carried a
scholing answer, so the server had nothing to re-validate. A crafted
POST could skip a requirement the wizard presents as mandatory.

IntakePolicy.RejectIncompleteScholing is the authority — three-valued
completeness (below threshold an answer is required; "nee" is legal and
still submits; punten only belong to a followed scholing), living in the
class that owns the constant so scripts/check-seam.sh keeps guarding the
FE/BE literal pair. Both submit paths call it; a violation 400s with
ProblemDetails and leaves the aanvraag a Concept. Gated on
Type == "intake" (the endpoint's switch lumps herregistratie with
intake, which has no scholing question), and guarded by `reject is null`
so a zero-uren submission is still decided on its merits.

Also fixes a live FE bug in the same rule: validateStep required punten
whenever scholingGevolgd was 'ja' regardless of lageUren, while the
template renders those fields only when lageUren — so answering 'ja'
then raising uren either blocked the user on an invisible field or
emitted aanvullendeScholing: undefined alongside punten. punten now
derives from aanvullendeScholing, so that combination is unrepresentable
in ValidIntake.

Note: EndpointTests' Worked_hours_submission_succeeds was itself
asserting the vulnerable payload ({ uren: 40 }, no answer) and needed a
complete answer added; the zero-hours rows are the ordering regression
net and are unmodified.

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

apps/ssp/src/app/herregistratie/ui/intake-wizard/intake-wizard.component.ts

@@ -387,7 +387,14 @@ export class IntakeWizardComponent {
     const s = this.state();
     if (s.tag !== 'Submitting') return;
     this.profile.beginHerregistratie();
-    const r = await this.draftSync.submit({ uren: s.data.uren });
+    // WP-69: the scholing answer rides along so the server can re-validate it as the
+    // authority (IntakePolicy.RejectIncompleteScholing) — undefined members are dropped by
+    // JSON.stringify, so a wizard above the threshold sends neither field.
+    const r = await this.draftSync.submit({
+      uren: s.data.uren,
+      aanvullendeScholing: s.data.aanvullendeScholing,
+      scholingPunten: s.data.punten,
+    });
     if (r.ok) {
       this.dispatch({ tag: 'SubmitConfirmed' });
       this.profile.confirmHerregistratie();