Enhance login UX with JS feedback and update docs

Added a new login.js script to provide visual feedback and prevent double submission on the login form. Updated login.html to include the script and wire up the login button. Clarified credential configuration instructions in README.md.

templates/login.html

@@ -4,6 +4,7 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>iNTERCEPT // Restricted Access</title>
+    <script src="{{ url_for('static', filename='js/core/login.js') }}"></script>
     <link rel="stylesheet" href="{{ url_for('static', filename='css/index.css') }}" />
     <link rel="stylesheet" href="{{ url_for('static', filename='css/login.css') }}" />
   </head>
@@ -48,7 +49,7 @@
             <input type="text" name="username" placeholder="OPERATOR ID" class="form-input" required autofocus autocomplete="off" />
             <input type="password" name="password" placeholder="ENCRYPTION KEY" class="form-input" required />
 
-            <button type="submit" class="landing-enter-btn">
+            <button type="submit" class="landing-enter-btn"  onclick="login(event)">
               <span class="btn-text">INITIALIZE SESSION</span>
             </button>
           </form>