清理城市农业类别 + 修复采集器LLM直接选题

清理:
- sustainability_cases.json移除GLO-001/CHN-001城市农业案例,替换为循环消费
- initial_cases.json移除case8东京垂直农场/case26城市屋顶农场
- strategy_topics_to_json.py移除B01/B05/D05三个种菜选题
- collector.py移除城市农业→循环消费映射,更新注释
- 删除fix_collector.py/test_image_gen.py/generate_images.py等遗留脚本
- 删除import_topics.py和automation/下旧版生成脚本

修复:
- collector.py _generate_topic_with_llm不再依赖搜索结果,无搜索时LLM直接生成
- run()始终调用LLM,不再要求web_search_results非空
- 替换sources.yaml中已失效的RSS源(澎湃/虎嗅/中新网→36氪/少数派)

automation/data/initial_cases.json

@@ -83,18 +83,6 @@
     "credibility_rating": "⭐⭐⭐⭐",
     "china_applicability": "⭐⭐⭐⭐"
   },
-  {
-    "id": 8,
-    "title": "东京垂直农场",
-    "field": "可持续生活系统",
-    "summary": "利用高层建筑内部空间进行多层种植，实现都市粮食自给。",
-    "key_metrics": "单位面积产量是传统农业的10倍，节水90%",
-    "date": "2024",
-    "source": "Spread 公司",
-    "source_url": "https://www.spread.co.jp/",
-    "credibility_rating": "⭐⭐⭐⭐⭐",
-    "china_applicability": "⭐⭐⭐"
-  },
   {
     "id": 9,
     "title": "纽约社区花园政策",
@@ -299,18 +287,6 @@
     "credibility_rating": "⭐⭐⭐",
     "china_applicability": "⭐⭐⭐⭐⭐"
   },
-  {
-    "id": 26,
-    "title": "城市屋顶农场：上海社区的粮食自给实验",
-    "field": "可持续生活系统",
-    "summary": "在上海某小区屋顶建设 200㎡ 农场，一年内生产 600kg 蔬菜，减少碳足迹 1.2 吨。",
-    "key_metrics": "蔬菜自给率 40%, 参与家庭 50 户, 社区互动提升 300%",
-    "date": "2024",
-    "source": "城市农业网",
-    "source_url": "https://www.urbanfarming.org/",
-    "credibility_rating": "⭐⭐⭐⭐",
-    "china_applicability": "⭐⭐⭐⭐⭐"
-  },
   {
     "id": 27,
     "title": "数字游民签证地图：2026 最新政策对比",

automation/data/sustainability_cases.json

@@ -1,21 +1,4 @@
 [
-  {
-    "id": "GLO-001",
-    "country": "Japan",
-    "category": "城市农业",
-    "title": "东京垂直农场：10平米 balcony 年产蔬菜 100kg",
-    "core_idea": "利用多层种植架和 LED 生长灯，在狭小阳台实现全年蔬菜生产",
-    "data_facts": "每平米年产 10kg，较传统方式节水 90%，投资回收期 1.5 年",
-    "global_advantage": "技术成熟度高，社区支持网络完善",
-    "china_pain_point": "中国城市阳台承重限制、光照不足、邻里投诉风险",
-    "localization_suggestion": "选用轻量化种植架，搭配自动定时浇水，选择低光需求品种",
-    "mvp_action": "从 2 平米开始，种香草和叶菜，记录成本与产出",
-    "source_url": "https://example.com/tokyo-vertical-farm",
-    "credibility_rating": "⭐⭐⭐⭐⭐",
-    "china_applicability": "⭐⭐⭐",
-    "collection_date": "2026-04-19",
-    "status": "已验证"
-  },
   {
     "id": "GLO-002",
     "country": "Sweden",
@@ -87,18 +70,18 @@
   {
     "id": "CHN-001",
     "country": "China",
-    "category": "城市农业",
-    "title": "上海阳台种菜年省 3000 元：居民自种调查",
-    "core_idea": "利用阳台空间种菜，实现部分蔬菜自给，降低生活成本",
-    "data_facts": "20 平米阳台年产蔬菜 100kg，节省买菜支出 3000 元，投入成本 2000 元",
-    "global_advantage": "中国城市人口密集，阳台空间普遍存在",
-    "china_pain_point": "缺乏种植知识，病虫害防治困难，物业可能干涉",
-    "localization_suggestion": "选择易种品种（番茄、辣椒、生菜），使用有机土，与邻居共享收获",
-    "mvp_action": "先种 5 盆香草，成功后再扩大",
-    "source_url": "https://www.bilibili.com/video/BV1xx411",
-    "credibility_rating": "⭐⭐⭐",
+    "category": "循环消费",
+    "title": "中国二手交易平台崛起：闲鱼转转让闲置物品年交易额超5000亿",
+    "core_idea": "通过二手交易平台，用户可以将闲置物品变现，降低消费成本",
+    "data_facts": "闲鱼年交易额超5000亿，用户数超3亿，每天上架商品超200万件",
+    "global_advantage": "中国移动互联网普及率高，二手交易习惯逐渐养成",
+    "china_pain_point": "信任机制不完善，假货和退换货纠纷多",
+    "localization_suggestion": "选择信誉高的卖家，优先购买有质检服务的商品",
+    "mvp_action": "整理家中闲置物品，本月在二手平台卖出3件",
+    "source_url": "https://www.goofish.com/",
+    "credibility_rating": "⭐⭐⭐⭐",
     "china_applicability": "⭐⭐⭐⭐⭐",
-    "collection_date": "2026-04-19",
+    "collection_date": "2026-05-20",
     "status": "已验证"
   }
 ]