feat(portal): public-form component architecture

Replace monolithic register/[eventSlug].vue with composable field
renderer, conditional-logic engine, stepper, and per-field components
driven by Form Builder schema. Adds flatpickr for date fields.

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

apps/portal/src/utils/formValidation.ts

@@ -0,0 +1,149 @@
+import { emailValidator, regexValidator, requiredValidator, urlValidator } from '@core/utils/validators'
+import { FormFieldType } from '@/types/formBuilder'
+import type { PublicFormField } from '@/types/formBuilder'
+
+export type Validator = (value: unknown) => true | string
+
+/**
+ * Build a list of client-side validators for a public form field.
+ * Runs in VTextField `:rules` and the stepper "current step valid"
+ * gate. Mirrors (a subset of) the backend relaxed rule set so the
+ * submitter gets feedback before the submit round-trip.
+ */
+export function getValidatorsForField(field: PublicFormField): Validator[] {
+  const rules: Validator[] = []
+  const v = field.validation_rules ?? {}
+
+  if (field.is_required) {
+    rules.push(value => {
+      const ok = requiredValidator(value)
+
+      return ok === true ? true : 'Dit veld is verplicht.'
+    })
+  }
+
+  switch (field.field_type) {
+    case FormFieldType.EMAIL:
+      rules.push(value => {
+        const ok = emailValidator(value)
+
+        return ok === true ? true : 'Vul een geldig e-mailadres in.'
+      })
+      break
+
+    case FormFieldType.URL:
+      rules.push(value => {
+        const ok = urlValidator(value)
+
+        return ok === true ? true : 'Vul een geldige URL in (beginnend met http:// of https://).'
+      })
+      break
+
+    case FormFieldType.PHONE:
+      rules.push(value => {
+        if (value === null || value === undefined || value === '') return true
+        const s = String(value).replace(/\s+/g, '')
+
+        return /^\+?[\d()-]{6,}$/.test(s) || 'Vul een geldig telefoonnummer in.'
+      })
+      break
+
+    case FormFieldType.NUMBER:
+      rules.push(value => {
+        if (value === null || value === undefined || value === '') return true
+        const n = Number(value)
+
+        return Number.isFinite(n) || 'Vul een geldig getal in.'
+      })
+      if (typeof v.min === 'number') {
+        const min = v.min
+        rules.push(value => {
+          if (value === null || value === undefined || value === '') return true
+          const n = Number(value)
+
+          return Number.isFinite(n) && n >= min ? true : `Minimaal ${min}.`
+        })
+      }
+      if (typeof v.max === 'number') {
+        const max = v.max
+        rules.push(value => {
+          if (value === null || value === undefined || value === '') return true
+          const n = Number(value)
+
+          return Number.isFinite(n) && n <= max ? true : `Maximaal ${max}.`
+        })
+      }
+      break
+
+    case FormFieldType.TEXT:
+    case FormFieldType.TEXTAREA:
+      if (typeof v.min === 'number') {
+        const min = v.min
+        rules.push(value => {
+          if (value === null || value === undefined || value === '') return true
+
+          return String(value).length >= min ? true : `Minimaal ${min} tekens.`
+        })
+      }
+      if (typeof v.max === 'number') {
+        const max = v.max
+        rules.push(value => {
+          if (value === null || value === undefined || value === '') return true
+
+          return String(value).length <= max ? true : `Maximaal ${max} tekens.`
+        })
+      }
+      if (typeof v.pattern === 'string' && v.pattern.length > 0) {
+        const pattern = v.pattern
+        rules.push(value => {
+          if (value === null || value === undefined || value === '') return true
+          const ok = regexValidator(value, pattern)
+
+          return ok === true ? true : 'Ongeldige invoer.'
+        })
+      }
+      break
+
+    case FormFieldType.MULTISELECT:
+    case FormFieldType.CHECKBOX_LIST:
+      if (typeof v.min_selections === 'number') {
+        const min = v.min_selections
+        rules.push(value => {
+          const arr = Array.isArray(value) ? value : []
+
+          return arr.length >= min ? true : `Kies er minimaal ${min}.`
+        })
+      }
+      if (typeof v.max_selections === 'number') {
+        const max = v.max_selections
+        rules.push(value => {
+          const arr = Array.isArray(value) ? value : []
+
+          return arr.length <= max ? true : `Kies er maximaal ${max}.`
+        })
+      }
+      break
+
+    default:
+      break
+  }
+
+  return rules
+}
+
+export function runValidators(rules: Validator[], value: unknown): string | true {
+  for (const rule of rules) {
+    const r = rule(value)
+    if (r !== true) return r
+  }
+
+  return true
+}
+
+export function isFieldValueEmpty(value: unknown): boolean {
+  if (value === null || value === undefined) return true
+  if (typeof value === 'string') return value.trim() === ''
+  if (Array.isArray(value)) return value.length === 0
+
+  return false
+}