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_prompt.go

@@ -213,7 +213,7 @@ func buildPromptContext(params map[string]interface{}) string {
 			return
 		}
 		switch key {
-		case "knowledge_group_ids", "knowledge_groups", "knowledge_context":
+		case "knowledge_group_ids", "knowledge_groups", "knowledge_context", "official_website", "website", "input_params":
 			return
 		}
 		if key == "outline_sections" && hasStructuredOutline(params["article_outline"]) {