feat: add cover image functionality for articles

- Implemented `resolveApiURL` function to handle various URL formats.
- Updated `ArticleDetail` and `UpdateArticleRequest` interfaces to include `cover_asset_url`.
- Enhanced `ArticleEditorView` to manage cover image uploads, including a new `CoverPickerModal` component.
- Added cover image requirements logic in `cover-requirements.ts` to enforce platform-specific cover image rules.
- Modified backend services to handle cover image uploads and validations, including checks for required cover images for specific platforms.
- Improved error handling for cover image requirements during article publishing.

server/internal/tenant/app/prompt_generate_service.go

@@ -181,7 +181,7 @@ func (s *PromptRuleGenerationService) GenerateFromRule(ctx context.Context, req
 	}
 
 	inputJSON, _ := json.Marshal(inputParams)
-	wizardStateJSON, _ := mergeArticleWizardState(nil, promptRuleGeneratingTitlePlaceholder, platformIDs)
+	wizardStateJSON, _ := mergeArticleWizardState(nil, promptRuleGeneratingTitlePlaceholder, platformIDs, nil)
 
 	tx, err := s.pool.Begin(ctx)
 	if err != nil {