feat: 知识库文档列表标题增加「清空」按钮——一键清空全部文档（分块与检索索引级联删除），清空前弹窗警告确认

crates/core/src/knowledge_base.rs

@@ -250,6 +250,15 @@ pub fn delete_document(db: &Connection, id: &str) -> Result<()> {
     Ok(())
 }
 
+/// 清空某知识库的全部文档（分块随外键级联删除，FTS 索引由触发器同步）。
+pub fn delete_all_documents(db: &Connection, kb_id: &str) -> Result<i64> {
+    let n = db.execute(
+        "DELETE FROM kb_documents WHERE kb_id = ?1",
+        params![kb_id],
+    )?;
+    Ok(n as i64)
+}
+
 /// 同一知识库下是否已存在来自该文件路径的文档（目录导入去重）。
 pub fn document_exists(db: &Connection, kb_id: &str, file_path: &str) -> Result<bool> {
     if file_path.is_empty() {
@@ -608,6 +617,32 @@ mod tests {
         assert!(hits.is_empty());
     }
 
+    #[test]
+    fn clear_all_documents_removes_everything() {
+        let conn = test_conn();
+        insert_knowledge_base(
+            &conn,
+            &KnowledgeBase {
+                id: "kb1".to_string(),
+                name: "测试库".to_string(),
+                description: String::new(),
+                chunk_size: 200,
+                chunk_overlap: 20,
+                doc_count: 0,
+                chunk_count: 0,
+                created_at: String::new(),
+                updated_at: String::new(),
+            },
+        )
+        .unwrap();
+        insert_doc(&conn, "d1", "第一份文档内容，用于清空测试。");
+        insert_doc(&conn, "d2", "第二份文档内容，同样会被清空。");
+        let n = delete_all_documents(&conn, "kb1").unwrap();
+        assert_eq!(n, 2);
+        assert!(list_documents(&conn, "kb1").unwrap().is_empty());
+        assert!(search(&conn, Some("kb1"), "清空", 10, 0).unwrap().is_empty());
+    }
+
     #[test]
     fn rechunk_changes_chunk_count() {
         let conn = test_conn();