feat: add console terminal io

- implement console-backed terminal input and resize polling

- implement console-backed terminal output helpers

- add example program for manual IO verification

src/Example/Program.cs

@@ -1,2 +1,72 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+using TinyTUI;
+using TinyTUI.Stdio;
+using TinyTUI.Stdout;
+
+using var input = new ConsoleTerminalInput();
+var output = new ConsoleTerminalOutput();
+var done = new ManualResetEventSlim();
+var latestSize = input.CurrentSize;
+
+output.ClearScreen();
+output.HideCursor();
+Render(output, latestSize, "等待输入");
+
+input.DataReceived += (_, data) =>
+{
+    if (data == "\x1b")
+    {
+        done.Set();
+        return;
+    }
+
+    Render(output, latestSize, $"按键: {FormatInput(data)}");
+};
+
+input.Resized += (_, size) =>
+{
+    latestSize = size;
+    Render(output, latestSize, "窗口尺寸已变化");
+};
+
+try
+{
+    input.Start();
+    done.Wait();
+}
+finally
+{
+    input.Stop();
+    output.ShowCursor();
+    output.Write("\r\n");
+    output.Flush();
+}
+
+static void Render(ConsoleTerminalOutput output, TerminalSize size, string message)
+{
+    output.ClearScreen();
+    output.Write("TinyTUI IO 示例\r\n");
+    output.Write("================\r\n");
+    output.Write($"尺寸: {size.Columns} x {size.Rows}\r\n");
+    output.Write($"{message}\r\n");
+    output.Write("\r\n");
+    output.Write("测试方式:\r\n");
+    output.Write("- 输入普通字符 观察按键内容\r\n");
+    output.Write("- 按方向键 Home End Delete F1-F12 观察原始序列\r\n");
+    output.Write("- 改变终端窗口大小 观察尺寸刷新\r\n");
+    output.Write("- 按 Esc 退出\r\n");
+    output.Flush();
+}
+
+static string FormatInput(string data)
+{
+    return string.Join(' ', data.Select(static c => c switch
+    {
+        '\r' => "\\r",
+        '\n' => "\\n",
+        '\t' => "\\t",
+        '\b' => "\\b",
+        '\x1b' => "\\x1b",
+        _ when char.IsControl(c) => $"\\x{(int)c:x2}",
+        _ => c.ToString(),
+    }));
+}