fix(hands): 搜索结果质量过滤 — 去除JS/CSS/广告等垃圾内容

问题：HTML解析器提取搜索引擎页面中的导航/脚本/广告片段，
导致搜索结果混入 function()/var/stylesheet 等垃圾文本。

修复：
- 新增 is_quality_result() 过滤函数，检查 title/snippet/url 质量
- 拒绝含 JS 关键词(function/var/const/window/document)的标题
- 拒绝含 CSS 标识(.css/stylesheet)的标题
- 拒绝过短(<2)或过长(>300)的标题
- 拒绝 javascript:/data: URL
- strip_html_tags 添加空白折叠 + 更多HTML实体
- 三个解析器(DDG/Bing/百度)全部接入质量过滤

测试: 68 PASS (新增8个质量过滤测试)

crates/zclaw-hands/src/hands/researcher.rs

@@ -556,6 +556,10 @@ impl ResearcherHand {
                 continue;
             }
 
+            if !is_quality_result(&title, &snippet, &url) {
+                continue;
+            }
+
             results.push(SearchResult {
                 title,
                 url,
@@ -645,6 +649,10 @@ impl ResearcherHand {
                 continue;
             }
 
+            if !is_quality_result(&title, &snippet, &url) {
+                continue;
+            }
+
             results.push(SearchResult {
                 title,
                 url,
@@ -725,6 +733,10 @@ impl ResearcherHand {
                 continue;
             }
 
+            if !is_quality_result(&title, &snippet, &url) {
+                continue;
+            }
+
             results.push(SearchResult {
                 title,
                 url,
@@ -1181,9 +1193,53 @@ fn strip_html_tags(s: &str) -> String {
         .replace(">", ">")
         .replace(""", "\"")
         .replace("'", "'")
-        .replace(" ", " ");
+        .replace(" ", " ")
+        .replace("'", "'")
+        .replace("/", "/");
 
-    result
+    // Collapse whitespace
+    let collapsed: String = result.split_whitespace().collect::<Vec<_>>().join(" ");
+    collapsed
+}
+
+/// Check if a search result is likely genuine (not navigation/ad/script garbage)
+fn is_quality_result(title: &str, snippet: &str, url: &str) -> bool {
+    // Title quality checks
+    let title_trimmed = title.trim();
+    if title_trimmed.len() < 2 || title_trimmed.len() > 300 {
+        return false;
+    }
+    // Reject titles with JavaScript/CSS indicators
+    let lower = title_trimmed.to_lowercase();
+    if lower.contains("function(") || lower.contains("var ") || lower.contains("const ")
+        || lower.contains("window.") || lower.contains("document.")
+        || lower.contains("{") || lower.contains("}")
+        || lower.starts_with("//") || lower.starts_with("/*")
+        || lower.contains("cookie") || lower.contains("navigator.")
+        || lower.contains(".css") || lower.contains("stylesheet")
+        || lower.contains("google-analytics") || lower.contains("gtag")
+    {
+        return false;
+    }
+
+    // URL quality checks
+    if url.contains("javascript:") || url.contains("data:") {
+        return false;
+    }
+    // Reject URLs that are just fragments or relative paths
+    if url.starts_with('#') || url.starts_with('/') && !url.starts_with("//") {
+        return false;
+    }
+
+    // Snippet quality — if snippet looks like code, reject
+    let snippet_lower = snippet.to_lowercase();
+    if snippet_lower.contains("function(") && snippet_lower.contains("return ")
+        || snippet_lower.contains("var ") && snippet_lower.contains("=")
+    {
+        return false;
+    }
+
+    true
 }
 
 /// Extract href URL from the first <a> tag in text
@@ -1913,4 +1969,48 @@ mod tests {
         };
         assert!(query.validate().is_ok());
     }
+
+    // --- Quality Filter Tests ---
+
+    #[test]
+    fn test_quality_rejects_javascript_title() {
+        assert!(!is_quality_result("function(x) { return x; }", "ok", "https://example.com"));
+    }
+
+    #[test]
+    fn test_quality_rejects_short_title() {
+        assert!(!is_quality_result("A", "snippet", "https://example.com"));
+    }
+
+    #[test]
+    fn test_quality_rejects_css_title() {
+        assert!(!is_quality_result(".stylesheet{color:red}", "ok", "https://example.com"));
+    }
+
+    #[test]
+    fn test_quality_rejects_javascript_url() {
+        assert!(!is_quality_result("Title", "snippet", "javascript:alert(1)"));
+    }
+
+    #[test]
+    fn test_quality_accepts_normal_result() {
+        assert!(is_quality_result("2024年中国医疗政策解读", "相关政策文件摘要", "https://www.gov.cn/policy"));
+    }
+
+    #[test]
+    fn test_quality_accepts_english_result() {
+        assert!(is_quality_result("Rust Programming Language", "A systems programming language", "https://www.rust-lang.org"));
+    }
+
+    #[test]
+    fn test_quality_rejects_long_title() {
+        let long_title: String = "x".repeat(301);
+        assert!(!is_quality_result(&long_title, "ok", "https://example.com"));
+    }
+
+    #[test]
+    fn test_strip_html_tags_collapses_whitespace() {
+        assert_eq!(strip_html_tags("<b>Hello</b>  <i>World</i>"), "Hello World");
+        assert_eq!(strip_html_tags("a\n\t b"), "a b");
+    }
 }