Add Range request test: verify dav-server partial content support

- test_range_request: GET with Range header returns 206 + partial content
- Verify Content-Range header present
- Test bytes=5-10 returns correct 6-byte slice

Tests: 289 passed, 0 failed

markbase-core/src/webdav.rs

@@ -1522,4 +1522,28 @@ mod integration_tests {
         assert!(xml.contains("D:acl"), "PROPFIND response should contain D:acl element");
         assert!(xml.contains("D:all"), "ACL should grant all privileges to all principals");
     }
+
+    #[tokio::test]
+    async fn test_range_request() {
+        let tmp = TempDir::new().unwrap();
+        std::fs::write(tmp.path().join("range_test.txt"), "0123456789abcdefghij").unwrap();
+        let handler = make_handler(&tmp);
+
+        // Range request: bytes=5-10
+        let req = http::Request::builder()
+            .method(Method::GET)
+            .uri("/range_test.txt")
+            .header("Range", "bytes=5-10")
+            .body(ReqBody::from(""))
+            .unwrap();
+        let res = handler.handle(req).await;
+        assert_eq!(res.status(), StatusCode::PARTIAL_CONTENT, "Range request should return 206");
+        assert!(
+            res.headers().contains_key("Content-Range"),
+            "Range response should include Content-Range header"
+        );
+        let (_, body) = collect_body(res).await;
+        let content = String::from_utf8(body).unwrap();
+        assert_eq!(content, "56789a", "Range bytes=5-10 should return '56789a' (6 bytes)");
+    }
 }