fix(portal): align FieldSectionPriority spec with WS-5b max_selected

Pre-existing breakage on main since WS-5b's validation_rules
canonicalisation renamed max_priorities → max_selected. Component
was migrated; the spec fixtures were not.

Four occurrences in
apps/portal/tests/components/public-form/FieldSectionPriority.spec.ts:

  - line 182, 253, 260: max_priorities used in fixture, the
    component's max_selected read returned undefined → test
    assertions on rendered max-cap behaviour failed (2 tests red)
  - line 220: also used max_priorities; test was accidentally
    passing because the value (99) was ignored and the component
    fell back to HARD_CAP = 5 which happened to match the
    "5 / 5" assertion. Now passes via the correct path (99 clamped
    to HARD_CAP via Math.min).

No component-side changes. No new test helpers. Pure fixture
key-rename matching ARCH-CONSOLIDATION-ADDENDUM-2026-04-24
WS-5b Uitvoering: "max_priorities → rule_type = max_selected:
semantically equivalent; two enum cases for one semantic = rot."

Pre: 111/113 passing, 2 failing.
Post: 113/113 passing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/portal/tests/components/public-form/FieldSectionPriority.spec.ts

@@ -179,7 +179,7 @@ describe('FieldSectionPriority', () => {
   it('respects validation_rules.max_priorities when present', async () => {
     state.data.value = [section({ id: 'a' }), section({ id: 'b' })]
     const w = mountPicker({
-      field: field({ validation_rules: { max_priorities: 1 } }),
+      field: field({ validation_rules: { max_selected: 1 } }),
       modelValue: [{ section_id: 'a', priority: 1 }],
     })
 
@@ -217,7 +217,7 @@ describe('FieldSectionPriority', () => {
       { section_id: 'e', priority: 5 },
     ]
     const w = mountPicker({
-      field: field({ validation_rules: { max_priorities: 99 } as Record<string, unknown> }),
+      field: field({ validation_rules: { max_selected: 99 } as Record<string, unknown> }),
       modelValue: ranked,
     })
 
@@ -250,14 +250,14 @@ describe('FieldSectionPriority', () => {
 
     // Not at cap — unranked cards must not carry the disabled marker.
     const notFull = mountPicker({
-      field: field({ validation_rules: { max_priorities: 3 } }),
+      field: field({ validation_rules: { max_selected: 3 } }),
       modelValue: [{ section_id: 'a', priority: 1 }],
     })
     expect(notFull.html()).not.toContain('section-priority-unranked-disabled')
 
     // Hit the cap — remaining unranked cards switch to the disabled class.
     const full = mountPicker({
-      field: field({ validation_rules: { max_priorities: 1 } }),
+      field: field({ validation_rules: { max_selected: 1 } }),
       modelValue: [{ section_id: 'a', priority: 1 }],
     })
     expect(full.html()).toContain('section-priority-unranked-disabled')