feat(utils, templates, docs): file-based templates + stronger README

templates/problem/csharp/Program.cs.tmpl

@@ -0,0 +1,24 @@
+// LeetCode {{NUMBER}}: {{NAME_TITLE}}
+// 難度: {{DIFFICULTY}}
+// 日期: {{DATE}}
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+public class Solution {
+    // TODO: 根據題意調整簽名
+    public int Solve(int[] nums) {
+        // 實作解法
+        return 0;
+    }
+}
+
+public class Program {
+    public static void Main() {
+        var s = new Solution();
+        // TODO: 可加入簡單輸入/輸出測試
+        Console.WriteLine("Hello LeetCode {{NUMBER}}!");
+    }
+}
+

templates/problem/csharp/csharp.csproj.tmpl

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+</Project>
+