feat(knowledge): Phase D 统一搜索 + 种子知识冷启动

- search/recommend API 返回 UnifiedSearchResult (文档+结构化双通道)
- POST /api/v1/knowledge/seed 种子知识冷启动 (幂等, admin权限)
- seed_knowledge service: 按标题+行业查重, source=distillation
- SearchRequest 扩展: search_structured/search_documents/industry_id

crates/zclaw-saas/src/knowledge/service.rs

@@ -582,6 +582,113 @@ pub async fn search(
     }).filter(|r| r.score >= min_score).collect())
 }
 
+// === 统一搜索（双通道合并） ===
+
+/// 统一搜索：同时检索文档通道和结构化通道
+pub async fn unified_search(
+    pool: &PgPool,
+    request: &SearchRequest,
+    viewer_account_id: Option<&str>,
+) -> SaasResult<UnifiedSearchResult> {
+    let limit = request.limit.unwrap_or(5).min(10);
+    let search_docs = request.search_documents.unwrap_or(true);
+    let search_struct = request.search_structured.unwrap_or(true);
+
+    // 文档通道
+    let documents = if search_docs {
+        search(
+            pool,
+            &request.query,
+            request.category_id.as_deref(),
+            limit,
+            request.min_score.unwrap_or(0.5),
+        ).await?
+    } else {
+        Vec::new()
+    };
+
+    // 结构化通道
+    let structured = if search_struct {
+        query_structured(
+            pool,
+            &StructuredQueryRequest {
+                query: request.query.clone(),
+                source_id: None,
+                industry_id: request.industry_id.clone(),
+                limit: Some(limit),
+            },
+            viewer_account_id,
+        ).await?
+    } else {
+        Vec::new()
+    };
+
+    Ok(UnifiedSearchResult {
+        documents,
+        structured,
+    })
+}
+
+// === 种子知识冷启动 ===
+
+/// 为指定行业插入种子知识（幂等）
+pub async fn seed_knowledge(
+    pool: &PgPool,
+    industry_id: &str,
+    category_id: &str,
+    items: &[(String, String, Vec<String>)], // (title, content, keywords)
+    system_account_id: &str,
+) -> SaasResult<usize> {
+    let mut created = 0;
+    for (title, content, keywords) in items {
+        if content.trim().is_empty() {
+            continue;
+        }
+        // 幂等：按标题 + source='distillation' + tags 含行业ID 查重
+        let exists: (i64,) = sqlx::query_as(
+            "SELECT COUNT(*) FROM knowledge_items \
+             WHERE title = $1 AND source = 'distillation' \
+             AND $2 = ANY(tags)"
+        )
+        .bind(title)
+        .bind(format!("industry:{}", industry_id))
+        .fetch_one(pool)
+        .await?;
+
+        if exists.0 > 0 {
+            continue;
+        }
+
+        let id = uuid::Uuid::new_v4().to_string();
+        let now = chrono::Utc::now();
+        let kw_json = serde_json::to_value(keywords).unwrap_or(serde_json::json!([]));
+        let tags = vec![
+            format!("industry:{}", industry_id),
+            "source:distillation".to_string(),
+        ];
+
+        sqlx::query(
+            "INSERT INTO knowledge_items \
+             (id, category_id, title, content, keywords, status, priority, visibility, account_id, source, tags, version, created_by, created_at, updated_at) \
+             VALUES ($1, $8, $2, $3, $4, 'active', 5, 'public', NULL, \
+                     'distillation', $5, 1, $6, $7, $7)"
+        )
+        .bind(&id)
+        .bind(title)
+        .bind(content)
+        .bind(&kw_json)
+        .bind(&tags)
+        .bind(system_account_id)
+        .bind(&now)
+        .bind(category_id)
+        .execute(pool)
+        .await?;
+
+        created += 1;
+    }
+    Ok(created)
+}
+
 // === 分析 ===
 
 /// 分析总览