feat: 首推理由行加 DAILY_FEATURED_REASON 开关

pick_why 本已渲染,现加开关默认开,空则省略(T6)。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

daily/format_wecom.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 import re
 from typing import Any
 
-from daily.config import wecom_skill_desc_limit
+from daily.config import env_bool, wecom_skill_desc_limit
 from daily.localize import LocalizeJob, localize_brief_descriptions, needs_chinese
 from daily.skills_group import group_skills_by_source
 from daily.text_utils import trim_brief
@@ -1096,7 +1096,8 @@ def build_wecom_report(
 
     lines.append(f"{ICONS['pick']} **今日首推**")
     lines.append(_format_pick_link(pick_command, title=pick_title, url=pick_url))
-    if pick_why:
+    # 首推「为什么值得点开」一句理由; DAILY_FEATURED_REASON=0 关闭, 空则省略
+    if pick_why and env_bool("DAILY_FEATURED_REASON", True):
         lines.append(f"> {pick_why}")
 
     return "\n".join(lines)