fix(content-gen): strip URLs and site-list sections from generated content

Forbid URLs/domains/markdown links across prompt rules (runtime, platform
templates, outline/imitation/title flows) and rename "官网" placeholder to
"官网信息" with explicit instructions that links are background only.
Add sanitizeGeneratedArticleMarkdown to strip URLs, HTML images, and
"网站列表/官网列表" labels from LLM output, wired into article, prompt-rule,
template, and outline generation. Drop the site_list outline section seed
and filter blocked outline keys in the wizard so stored drafts cannot
resurrect it.

server/internal/tenant/app/template_service.go

@@ -520,7 +520,7 @@ func (s *TemplateService) executeGeneration(ctx context.Context, job generationJ
 		return
 	}
 
-	content := strings.TrimSpace(result.Content)
+	content := sanitizeGeneratedArticleMarkdown(result.Content)
 	if content == "" {
 		s.failGeneration(ctx, job, title, "llm_generate", fmt.Errorf("模型返回空内容"))
 		return