refactor: migrate from templ to html/template

templates/login.gohtml

@@ -0,0 +1,22 @@
+{{define "title"}}Login{{end}}
+{{define "content"}}
+  <div class="max-w-md mx-auto mt-20">
+    <h2 class="text-3xl font-bold mb-8 text-center">Login</h2>
+    {{if .Error}}
+      <div class="bg-red-500 text-white p-3 rounded mb-4">{{.Error}}</div>
+    {{end}}
+    <form method="POST" action="/login" class="space-y-4">
+      <div>
+        <label for="username" class="block text-sm font-medium mb-2">Username</label>
+        <input type="text" id="username" name="username" value="{{.Username}}" class="w-full p-2 rounded bg-gray-800 border border-gray-700 focus:border-blue-500 outline-none">
+      </div>
+      <div>
+        <label for="password" class="block text-sm font-medium mb-2">Password</label>
+        <input type="password" id="password" name="password" class="w-full p-2 rounded bg-gray-800 border border-gray-700 focus:border-blue-500 outline-none">
+      </div>
+      <button type="submit" class="w-full bg-blue-600 hover:bg-blue-700 text-white font-bold py-2 px-4 rounded">
+        Login
+      </button>
+    </form>
+  </div>
+{{end}}