fix(hands): 搜索引擎优先级调整 — 国内用户优先百度+Bing CN

中国用户无法使用 Google/DuckDuckGo(被墙)，调整策略:
1. Google/DuckDuckGo 路由降级到百度(非Bing)
2. search_native() 所有查询统一百度+Bing CN并行
3. DDG仅作为最后后备(主引擎都空时才尝试)
4. 移除 CJK 分支逻辑 — 百度+Bing CN 对中英文都有效

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

@@ -324,11 +324,13 @@ impl ResearcherHand {
                 self.search_native(&query.query, max_results).await?
             }
             SearchEngine::DuckDuckGo => {
-                self.search_duckduckgo_html(&query.query, max_results).await?
+                // DDG在国内不可用，降级到百度
+                tracing::warn!(target: "researcher", "DuckDuckGo在国内不可用，降级到百度");
+                self.search_baidu(&query.query, max_results).await?
             }
             SearchEngine::Google => {
-                tracing::warn!(target: "researcher", "Google 不支持直接搜索，降级到 Bing");
-                self.search_bing(&query.query, max_results).await?
+                tracing::warn!(target: "researcher", "Google在国内不可用，降级到百度");
+                self.search_baidu(&query.query, max_results).await?
             }
             SearchEngine::Bing => {
                 self.search_bing(&query.query, max_results).await?
@@ -348,48 +350,32 @@ impl ResearcherHand {
         Ok(results)
     }
 
-    /// Rust-native multi-engine search with Chinese auto-detection
+    /// Rust-native multi-engine search — optimized for China mainland users
+    /// Priority: Baidu + Bing CN (both always work in China)
+    /// DuckDuckGo as optional fallback (may be blocked by GFW)
     async fn search_native(&self, query: &str, max_results: usize) -> Result<Vec<SearchResult>> {
-        let has_cjk = query.chars().any(|c| is_cjk_char(c));
-
-        // Strategy: try multiple engines in parallel, merge results
         let mut all_results = Vec::new();
 
-        if has_cjk {
-            // Chinese query: Bing CN + Baidu + DuckDuckGo in parallel
-            let bing_fut = self.search_bing(query, max_results);
-            let baidu_fut = self.search_baidu(query, max_results);
-            let ddg_fut = self.search_duckduckgo_html(query, max_results);
+        // Always use Baidu + Bing CN in parallel (both work in China)
+        let baidu_fut = self.search_baidu(query, max_results);
+        let bing_fut = self.search_bing(query, max_results);
 
-            let (bing_res, baidu_res, ddg_res) = tokio::join!(
-                async { bing_fut.await },
-                async { baidu_fut.await },
-                async { ddg_fut.await },
-            );
+        let (baidu_res, bing_res) = tokio::join!(
+            async { baidu_fut.await },
+            async { bing_fut.await },
+        );
 
-            if let Ok(r) = bing_res {
-                all_results.extend(r);
-            }
-            if let Ok(r) = baidu_res {
-                all_results.extend(r);
-            }
-            if let Ok(r) = ddg_res {
-                all_results.extend(r);
-            }
-        } else {
-            // English query: DuckDuckGo HTML first, then Bing
-            let ddg_fut = self.search_duckduckgo_html(query, max_results);
-            let bing_fut = self.search_bing(query, max_results);
+        if let Ok(r) = baidu_res {
+            all_results.extend(r);
+        }
+        if let Ok(r) = bing_res {
+            all_results.extend(r);
+        }
 
-            let (ddg_res, bing_res) = tokio::join!(
-                async { ddg_fut.await },
-                async { bing_fut.await },
-            );
-
-            if let Ok(r) = ddg_res {
-                all_results.extend(r);
-            }
-            if let Ok(r) = bing_res {
+        // If both primary engines returned nothing, try DDG as last resort
+        if all_results.is_empty() {
+            tracing::info!(target: "researcher", "Primary engines empty, trying DuckDuckGo as fallback");
+            if let Ok(r) = self.search_duckduckgo_html(query, max_results).await {
                 all_results.extend(r);
             }
         }