implemented 0.db as admin database architecture + updated test file

tests/debug_hset_simple.rs

@@ -19,6 +19,7 @@ async fn debug_hset_return_value() {
         encrypt: false,
         encryption_key: None,
         backend: herodb::options::BackendType::Redb,
+        admin_secret: "test-admin".to_string(),
     };
     
     let mut server = Server::new(option).await;
@@ -40,12 +41,19 @@ async fn debug_hset_return_value() {
     
     // Connect and test HSET
     let mut stream = TcpStream::connect("127.0.0.1:16390").await.unwrap();
+
+    // Acquire ReadWrite permissions for this new connection
+    let handshake = "*4\r\n$6\r\nSELECT\r\n$1\r\n0\r\n$3\r\nKEY\r\n$10\r\ntest-admin\r\n";
+    stream.write_all(handshake.as_bytes()).await.unwrap();
+    let mut buffer = [0; 1024];
+    let n = stream.read(&mut buffer).await.unwrap();
+    let resp = String::from_utf8_lossy(&buffer[..n]);
+    assert!(resp.contains("OK"), "Failed SELECT handshake: {}", resp);
     
     // Send HSET command
     let cmd = "*4\r\n$4\r\nHSET\r\n$4\r\nhash\r\n$6\r\nfield1\r\n$6\r\nvalue1\r\n";
     stream.write_all(cmd.as_bytes()).await.unwrap();
     
-    let mut buffer = [0; 1024];
     let n = stream.read(&mut buffer).await.unwrap();
     let response = String::from_utf8_lossy(&buffer[..n]);