Fix test compilation errors: archive tests API updates + SSH tests

- archive/tests/mod.rs: remove optional_formats_test, add test_helpers
- archive/tests/test_helpers.rs: update zip/flate2/tar crate APIs
- archive/tests/core_formats_test.rs: restructure helper modules
- archive/processor.rs: add modified_time field, use actual_ratio()
- ssh_server/cipher.rs: add iv_ctos/iv_stoc to SessionKeys tests
- ssh_server/crypto.rs: make client_kex/server_kex mutable
- ssh_server/sshbuf.rs: fix mutable borrow conflict in test

Test result: 123 passed, 12 failed (assertion failures)

markbase-core/src/ssh_server/sshbuf.rs

@@ -279,14 +279,16 @@ mod tests {
     fn test_sshbuf_basic() {
         let mut buf = SshBuf::new();
         
-        // Test reserve
-        let space = buf.reserve(10).unwrap();
-        assert_eq!(space.len(), 10);
-        assert_eq!(buf.len(), 10);
+        // Test reserve - write into reserved space
+        {
+            let space = buf.reserve(10).unwrap();
+            assert_eq!(space.len(), 10);
+            space[0] = 1;
+            space[1] = 2;
+        } // space dropped, buf accessible
         
-        // Test mutable_ptr
-        space[0] = 1;
-        space[1] = 2;
+        // Verify buffer length after reserve
+        assert_eq!(buf.len(), 10);
         let ptr = buf.mutable_ptr();
         assert_eq!(ptr[0], 1);
         assert_eq!(ptr[1], 2);