[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/UploadModelDialog.vue

@@ -0,0 +1,108 @@
+<template>
+  <div class="upload-model-dialog flex flex-col justify-between gap-6 p-4 pt-6">
+    <!-- Step 1: Enter URL -->
+    <UploadModelUrlInput
+      v-if="currentStep === 1"
+      v-model="wizardData.url"
+      :error="uploadError"
+    />
+
+    <!-- Step 2: Confirm Metadata -->
+    <UploadModelConfirmation
+      v-else-if="currentStep === 2"
+      v-model="selectedModelType"
+      :metadata="wizardData.metadata"
+    />
+
+    <!-- Step 3: Upload Progress -->
+    <UploadModelProgress
+      v-else-if="currentStep === 3"
+      :status="uploadStatus"
+      :error="uploadError"
+      :metadata="wizardData.metadata"
+      :model-type="selectedModelType"
+    />
+
+    <!-- Navigation Footer -->
+    <UploadModelFooter
+      :current-step="currentStep"
+      :is-fetching-metadata="isFetchingMetadata"
+      :is-uploading="isUploading"
+      :can-fetch-metadata="canFetchMetadata"
+      :can-upload-model="canUploadModel"
+      :upload-status="uploadStatus"
+      @back="goToPreviousStep"
+      @fetch-metadata="handleFetchMetadata"
+      @upload="handleUploadModel"
+      @close="handleClose"
+    />
+  </div>
+</template>
+
+<script setup lang="ts">
+import { onMounted } from 'vue'
+
+import UploadModelConfirmation from '@/platform/assets/components/UploadModelConfirmation.vue'
+import UploadModelFooter from '@/platform/assets/components/UploadModelFooter.vue'
+import UploadModelProgress from '@/platform/assets/components/UploadModelProgress.vue'
+import UploadModelUrlInput from '@/platform/assets/components/UploadModelUrlInput.vue'
+import { useModelTypes } from '@/platform/assets/composables/useModelTypes'
+import { useUploadModelWizard } from '@/platform/assets/composables/useUploadModelWizard'
+import { useDialogStore } from '@/stores/dialogStore'
+
+const dialogStore = useDialogStore()
+const { modelTypes, fetchModelTypes } = useModelTypes()
+
+const emit = defineEmits<{
+  'upload-success': []
+}>()
+
+const {
+  currentStep,
+  isFetchingMetadata,
+  isUploading,
+  uploadStatus,
+  uploadError,
+  wizardData,
+  selectedModelType,
+  canFetchMetadata,
+  canUploadModel,
+  fetchMetadata,
+  uploadModel,
+  goToPreviousStep
+} = useUploadModelWizard(modelTypes)
+
+async function handleFetchMetadata() {
+  await fetchMetadata()
+}
+
+async function handleUploadModel() {
+  const success = await uploadModel()
+  if (success) {
+    emit('upload-success')
+  }
+}
+
+function handleClose() {
+  dialogStore.closeDialog({ key: 'upload-model' })
+}
+
+onMounted(() => {
+  fetchModelTypes()
+})
+</script>
+
+<style scoped>
+.upload-model-dialog {
+  width: 90vw;
+  max-width: 800px;
+  min-height: 400px;
+}
+
+@media (min-width: 640px) {
+  .upload-model-dialog {
+    width: auto;
+    min-width: 600px;
+  }
+}
+</style>