feat: registration field polish, multi-category tags, file uploads, Partner icon

- Restructure field editor dialog: move Options section to bottom with
  divider and subheader, fix delete button with flex layout
- Change tag_category (single string) to tag_categories (JSON array)
  supporting multiple category selection in tag picker fields
- Portal tag picker now groups tags by category with subheaders
- Add generic file upload endpoint (FileUploadService + UploadController)
- Replace email branding logo URL text field with ImageUploadField
- Update Partner crowd type default icon to tabler-affiliate
- Apply changes consistently to both field and template dialogs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/app/src/components/common/ImageUploadField.vue

@@ -0,0 +1,131 @@
+<script setup lang="ts">
+import { apiClient } from '@/lib/axios'
+
+interface Props {
+  modelValue: string | null
+  label?: string
+  purpose: 'logo' | 'banner' | 'icon' | 'avatar'
+  hint?: string
+  previewHeight?: number
+}
+
+const props = withDefaults(defineProps<Props>(), {
+  label: undefined,
+  hint: undefined,
+  previewHeight: 120,
+})
+
+const emit = defineEmits<{
+  'update:modelValue': [url: string | null]
+}>()
+
+const fileInput = ref<HTMLInputElement | null>(null)
+const uploading = ref(false)
+const error = ref('')
+
+function triggerFileInput() {
+  fileInput.value?.click()
+}
+
+async function onFileSelected(event: Event) {
+  const input = event.target as HTMLInputElement
+  const file = input.files?.[0]
+  if (!file) return
+
+  uploading.value = true
+  error.value = ''
+
+  try {
+    const formData = new FormData()
+    formData.append('file', file)
+    formData.append('purpose', props.purpose)
+
+    const { data } = await apiClient.post<{ data: { url: string } }>('/upload/image', formData, {
+      headers: { 'Content-Type': 'multipart/form-data' },
+    })
+
+    emit('update:modelValue', data.data.url)
+  }
+  catch (e: unknown) {
+    const axiosError = e as { response?: { data?: { message?: string } } }
+    error.value = axiosError.response?.data?.message ?? 'Upload mislukt'
+  }
+  finally {
+    uploading.value = false
+    if (input) input.value = ''
+  }
+}
+
+function remove() {
+  emit('update:modelValue', null)
+  error.value = ''
+}
+</script>
+
+<template>
+  <div>
+    <label
+      v-if="label"
+      class="text-body-2 text-medium-emphasis d-block mb-1"
+    >
+      {{ label }}
+    </label>
+
+    <div
+      v-if="modelValue"
+      class="mb-2"
+    >
+      <VImg
+        :src="modelValue"
+        :max-height="previewHeight"
+        max-width="300"
+        class="rounded border"
+        cover
+      />
+    </div>
+
+    <div class="d-flex align-center gap-2">
+      <VBtn
+        :variant="modelValue ? 'tonal' : 'elevated'"
+        color="primary"
+        size="small"
+        prepend-icon="tabler-upload"
+        :loading="uploading"
+        @click="triggerFileInput"
+      >
+        {{ modelValue ? 'Vervangen' : 'Uploaden' }}
+      </VBtn>
+      <VBtn
+        v-if="modelValue"
+        variant="text"
+        color="error"
+        size="small"
+        prepend-icon="tabler-trash"
+        @click="remove"
+      >
+        Verwijderen
+      </VBtn>
+    </div>
+
+    <input
+      ref="fileInput"
+      type="file"
+      accept="image/*"
+      style="display: none;"
+      @change="onFileSelected"
+    >
+
+    <div
+      v-if="error"
+      class="text-caption text-error mt-1"
+    >
+      {{ error }}
+    </div>
+    <div
+      v-else-if="hint"
+      class="text-caption text-medium-emphasis mt-1"
+    >
+      {{ hint }}
+    </div>
+  </div>
+</template>