[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/components/common/UrlInput.vue

@@ -35,6 +35,7 @@ import { ValidationState } from '@/utils/validationUtil'
 const props = defineProps<{
   modelValue: string
   validateUrlFn?: (url: string) => Promise<boolean>
+  disableValidation?: boolean
 }>()
 
 const emit = defineEmits<{
@@ -101,6 +102,8 @@ const defaultValidateUrl = async (url: string): Promise<boolean> => {
 }
 
 const validateUrl = async (value: string) => {
+  if (props.disableValidation) return
+
   if (validationState.value === ValidationState.LOADING) return
 
   const url = cleanInput(value)