feat(phase1): OpenRouter采集器接入PostgreSQL，数据链路闭环

- 将 fetch_openrouter.go 的 summarize() 实现为 PostgreSQL upsert
- 新增 -db 参数和 DATABASE_URL 环境变量支持
- 打通 models + model_prices 表的最小可运行链路
- 创建 llm_intelligence 数据库并运行 migration
- 前端 Explorer 验证 T-3.2~T-3.5 全部通过
- 日报生成器正常产出 Markdown 和 latest_models.json

scripts/testdata/openrouter_models_sample.json

@@ -0,0 +1,33 @@
+{
+  "data": [
+    {
+      "id": "openai/gpt-4o",
+      "name": "GPT-4o",
+      "created": 1717556344,
+      "description": "Most intelligent model for complex tasks",
+      "context_length": 128000,
+      "capabilities": ["vision", "function_calling", "json_mode"],
+      "pricing": {
+        "input": 2.5,
+        "output": 10.0
+      }
+    },
+    {
+      "id": "deepseek-ai/DeepSeek-V3",
+      "created": 1716931200,
+      "context_length": 64000,
+      "pricing": {
+        "prompt": 0.1,
+        "completion": 0.3
+      }
+    },
+    {
+      "id": "mistralai/Mistral-7B:free",
+      "name": "Mistral-7B Free",
+      "created": 1715308800,
+      "context_length": 32768,
+      "capabilities": ["text"],
+      "pricing": {}
+    }
+  ]
+}