fix(data): complete verified contracts and source maintenance (#114)

docs/data-sources/api-providers/serper.md

@@ -0,0 +1,49 @@
+# Serper
+
+首页可读，但未找到认证请求与完整响应契约，本轮不能据此确认 X-API-KEY、organic 等字段。需官方控制台文档或示例。
+
+数据区中的 claims 是复核边界，pending 字段是当前配置快照，不能当官方证明。enabled/priority/timeout 是产品策略，未复制到合同中。更新合同必须重新读官方正文、记录实际证明字段；结构校验不等于账号可用。
+
+<!-- data-source:start -->
+```json
+{
+  "kind": "api-contract",
+  "config": "api-providers/web-search/serper.json",
+  "checkedAt": "2026-10-03",
+  "status": "pending",
+  "sources": [
+    {
+      "url": "https://serper.dev/",
+      "retrieval": "fetched",
+      "checkedAt": "2026-10-03",
+      "resolvedUrl": "https://serper.dev/",
+      "contentSha256": "ad5b407c075ef4357fc4674cafb1b215d2713dc17d65d0607504bfec29b62c6c"
+    }
+  ],
+  "verifiedFields": [],
+  "claims": {
+    "endpoint": "https://google.serper.dev/search",
+    "method": "POST",
+    "auth": {
+      "type": "header",
+      "headerName": "X-API-KEY",
+      "apiKeyRef": "serper"
+    },
+    "request": {
+      "bodyTemplate": {
+        "q": "${query}",
+        "num": "${maxResults}"
+      }
+    },
+    "response": {
+      "resultsPath": "organic",
+      "item": {
+        "titlePath": "title",
+        "urlPath": "link",
+        "snippetPath": "snippet"
+      }
+    }
+  }
+}
+```
+<!-- data-source:end -->