Add Two-Factor Authentication (2FA) support and key management features

- Implemented 2FA management in admin panel with enable/disable options.
- Added QR code display for 2FA setup and input for TOTP codes in login and pickup forms.
- Introduced key management section for generating, loading, and clearing RSA key pairs.
- Enhanced file upload and sharing functionality with optional 2FA.
- Added buttons for switching between development and production modes in admin panel.
- Updated API documentation to reflect new 2FA and key management features.

templates/pickup.html

@@ -45,8 +45,24 @@
             <!-- File Info -->
             <div class="form-group">
                 <p style="color: #00ff99; margin-bottom: 15px;">File ID: <code>{{ file_id }}</code></p>
+                {% if require_2fa %}
+                <p style="color: #ffaa00; margin-bottom: 15px;">🔒 This file requires 2FA (TOTP) authentication.</p>
+                {% endif %}
             </div>
 
+            {% if require_2fa %}
+            <div class="form-group" style="border: 2px solid #ffaa00; padding: 15px; margin-bottom: 20px; border-radius: 5px;">
+                <h3 style="color: #ffaa00; margin-top: 0;">⚠️ 2FA Required</h3>
+                <p style="color: #ccc;">
+                    <strong>You should have already set up 2FA when uploading this file.</strong><br>
+                    Enter the 6-digit code from your authenticator app below.
+                </p>
+                <p style="color: #ff6b6b; font-size: 0.9em;">
+                    If you didn't set up 2FA during upload, you won't be able to access this file.
+                </p>
+            </div>
+            {% endif %}
+
             <!-- Pickup Form -->
             <form method="POST" class="form-group">
                 <div class="form-group">
@@ -65,6 +81,19 @@
                            autocomplete="off" />
                 </div>
 
+                {% if require_2fa %}
+                <div class="form-group">
+                    <input type="text" 
+                           name="totp_code" 
+                           placeholder="6-Digit Authenticator Code" 
+                           required 
+                           maxlength="6" 
+                           pattern="[0-9]{6}"
+                           autocomplete="off"
+                           style="text-align: center; font-size: 1.2em; letter-spacing: 0.2em;" />
+                </div>
+                {% endif %}
+
                 <div class="button-group">
                     <button type="submit">Decrypt and Download</button>
                 </div>