[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/UploadModelFooter.vue

@@ -0,0 +1,72 @@
+<template>
+  <div class="flex justify-end gap-2">
+    <TextButton
+      v-if="currentStep !== 1 && currentStep !== 3"
+      :label="$t('g.back')"
+      type="secondary"
+      size="md"
+      :disabled="isFetchingMetadata || isUploading"
+      @click="emit('back')"
+    />
+    <span v-else />
+
+    <IconTextButton
+      v-if="currentStep === 1"
+      :label="$t('g.continue')"
+      type="primary"
+      size="md"
+      :disabled="!canFetchMetadata || isFetchingMetadata"
+      @click="emit('fetchMetadata')"
+    >
+      <template #icon>
+        <i
+          v-if="isFetchingMetadata"
+          class="icon-[lucide--loader-circle] animate-spin"
+        />
+      </template>
+    </IconTextButton>
+    <IconTextButton
+      v-else-if="currentStep === 2"
+      :label="$t('assetBrowser.upload')"
+      type="primary"
+      size="md"
+      :disabled="!canUploadModel || isUploading"
+      @click="emit('upload')"
+    >
+      <template #icon>
+        <i
+          v-if="isUploading"
+          class="icon-[lucide--loader-circle] animate-spin"
+        />
+      </template>
+    </IconTextButton>
+    <TextButton
+      v-else-if="currentStep === 3 && uploadStatus === 'success'"
+      :label="$t('assetBrowser.finish')"
+      type="primary"
+      size="md"
+      @click="emit('close')"
+    />
+  </div>
+</template>
+
+<script setup lang="ts">
+import IconTextButton from '@/components/button/IconTextButton.vue'
+import TextButton from '@/components/button/TextButton.vue'
+
+defineProps<{
+  currentStep: number
+  isFetchingMetadata: boolean
+  isUploading: boolean
+  canFetchMetadata: boolean
+  canUploadModel: boolean
+  uploadStatus: 'idle' | 'uploading' | 'success' | 'error'
+}>()
+
+const emit = defineEmits<{
+  (e: 'back'): void
+  (e: 'fetchMetadata'): void
+  (e: 'upload'): void
+  (e: 'close'): void
+}>()
+</script>