[feat] Add Civitai model upload wizard (#6694)

## Summary
Adds a complete model upload workflow that allows users to import models
from Civitai URLs directly into their library.

## Changes
- **Multi-step wizard**: URL input → metadata confirmation → upload
progress
- **Components**: UploadModelDialog, UploadModelUrlInput,
UploadModelConfirmation, UploadModelProgress, UploadModelDialogHeader
- **API integration**: New assetService methods for metadata retrieval
and URL-based uploads
- **Model type management**: useModelTypes composable for fetching and
formatting available model types
- **UX improvements**: Optional validation bypass for UrlInput component
- **Localization**: 26 new i18n strings for the upload workflow

## Review Focus
- Error handling for failed uploads and metadata retrieval
- Model type detection and selection logic
- Dialog state management across multi-step workflow

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6694-feat-Add-Civitai-model-upload-wizard-2ab6d73d36508193b3b1dd67c7cc5a09)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/platform/assets/components/UploadModelConfirmation.vue

@@ -0,0 +1,58 @@
+<template>
+  <div class="flex flex-col gap-4">
+    <!-- Model Info Section -->
+    <div class="flex flex-col gap-2">
+      <p class="text-sm text-muted m-0">
+        {{ $t('assetBrowser.modelAssociatedWithLink') }}
+      </p>
+      <p class="text-sm mt-0">
+        {{ metadata?.name || metadata?.filename }}
+      </p>
+    </div>
+
+    <!-- Model Type Selection -->
+    <div class="flex flex-col gap-2">
+      <label class="text-sm text-muted">
+        {{ $t('assetBrowser.modelTypeSelectorLabel') }}
+      </label>
+      <SingleSelect
+        v-model="selectedModelType"
+        :label="
+          isLoading
+            ? $t('g.loading')
+            : $t('assetBrowser.modelTypeSelectorPlaceholder')
+        "
+        :options="modelTypes"
+        :disabled="isLoading"
+      />
+      <div class="flex items-center gap-2 text-sm text-muted">
+        <i class="icon-[lucide--info]" />
+        <span>{{ $t('assetBrowser.notSureLeaveAsIs') }}</span>
+      </div>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { computed } from 'vue'
+
+import SingleSelect from '@/components/input/SingleSelect.vue'
+import { useModelTypes } from '@/platform/assets/composables/useModelTypes'
+import type { AssetMetadata } from '@/platform/assets/schemas/assetSchema'
+
+const props = defineProps<{
+  modelValue: string | undefined
+  metadata: AssetMetadata | null
+}>()
+
+const emit = defineEmits<{
+  'update:modelValue': [value: string | undefined]
+}>()
+
+const { modelTypes, isLoading } = useModelTypes()
+
+const selectedModelType = computed({
+  get: () => props.modelValue ?? null,
+  set: (value: string | null) => emit('update:modelValue', value ?? undefined)
+})
+</script>