refactor: writer.py 移除文件系统写入代码，HTML 仅持久化到数据库

删除 RELEASE_DIR、release_dir、out_path.write_text 等文件系统相关代码，
save_html 改为仅调用 save_article() 写入 articles 表。
避免后期维护时文件系统和数据库双源不一致的问题。

scripts/writer.py

@@ -18,7 +18,6 @@ import mistune
 
 DATA_DIR = PROJECT_ROOT / "automation" / "data"
 OUTLINE_DIR = DATA_DIR / "outlines"
-RELEASE_DIR = DATA_DIR / "releases"
 TEMPLATES_DIR = PROJECT_ROOT / "automation" / "templates"
 LOGS_DIR = PROJECT_ROOT / "automation" / "logs"
 TODAY = datetime.datetime.now().strftime("%Y-%m-%d")
@@ -59,8 +58,6 @@ class Writer:
         if not outline_file.exists():
             raise FileNotFoundError(f"Outline not found: {outline_file}")
         self.outline_content = outline_file.read_text(encoding='utf-8')
-        self.release_dir = RELEASE_DIR / TODAY
-        self.release_dir.mkdir(parents=True, exist_ok=True)
         research_file = DATA_DIR / "research" / TODAY / f"{topic_id}_research.md"
         self.research_notes = research_file.read_text(encoding='utf-8') if research_file.exists() else ""
 
@@ -417,19 +414,14 @@ class Writer:
 
         return html
 
-    def save_html(self, html: str, platform: str) -> Path:
-        out_dir = self.release_dir / platform
-        out_dir.mkdir(parents=True, exist_ok=True)
-        filename = f"{platform}_{self.topic_id}.html"
-        out_path = out_dir / filename
-        out_path.write_text(html, encoding='utf-8')
-        logger.info(f"HTML 生成: {out_path}")
+    def save_html(self, html: str, platform: str) -> str:
         try:
             save_article(self.topic_id, platform, html)
             logger.info(f"文章写入数据库: {platform}_{self.topic_id}")
+            return f"db:{platform}_{self.topic_id}"
         except Exception as e:
             logger.warning(f"数据库保存失败: {e}")
-        return out_path
+            return ""
 
     def mark_draft(self):
         update_topic_status(self.topic_id, 'review')