Security hardening: env-based config, CSRF protection, secure code generation, plus presenter management and email communications system

- Move all credentials from hardcoded to .env with python-dotenv (add .env.example template and .gitignore)
- Add CSRF token generation and validation on all state-changing requests
- Replace random.choices with secrets.choice for all secure code generation
- Add session cookie security headers (HttpOnly, Secure, SameSite)
- Add presenter management: assign/remove presenters to breakout sessions, presenter QR scanning
- Add email communications system: templates per event, custom email sending, sent email tracking
- Add staff/organizer profile pages with staff code display
- New DB tables: event_email_templates, sent_emails, user_communications
- New DB columns: staff.reminder_count/reminder_dates, breakout_session_organizers.presenter_code
- Expand English translation strings across all new features

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

templates/organizer/edit_event_confirm.html

@@ -3,82 +3,6 @@
 {% block title %}{{ 'confirm_changes'|t }} - {{ event.name }}{% endblock %}
 
 {% block content %}
-<style>
-.modal-overlay {
-    position: fixed;
-    top: 0;
-    left: 0;
-    width: 100%;
-    height: 100%;
-    background: rgba(0, 0, 0, 0.5);
-    display: flex;
-    align-items: center;
-    justify-content: center;
-    z-index: 1000;
-}
-.modal-content {
-    background: #fff;
-    border-radius: 12px;
-    padding: 30px;
-    max-width: 500px;
-    width: 90%;
-    max-height: 80vh;
-    overflow-y: auto;
-    box-shadow: 0 10px 40px rgba(0,0,0,0.2);
-}
-.modal-header {
-    margin-bottom: 20px;
-}
-.modal-header h2 {
-    margin: 0 0 10px 0;
-    color: #2c3e50;
-}
-.modal-header p {
-    margin: 0;
-    color: #666;
-}
-.changes-list {
-    background: #f8f9fa;
-    border-radius: 8px;
-    padding: 15px;
-    margin-bottom: 20px;
-}
-.change-item {
-    padding: 10px 0;
-    border-bottom: 1px solid #e9ecef;
-}
-.change-item:last-child {
-    border-bottom: none;
-}
-.change-label {
-    font-weight: 600;
-    color: #495057;
-    margin-bottom: 5px;
-}
-.change-values {
-    display: flex;
-    gap: 10px;
-    align-items: center;
-}
-.old-value {
-    color: #dc3545;
-    text-decoration: line-through;
-    opacity: 0.7;
-}
-.arrow {
-    color: #666;
-}
-.new-value {
-    color: #28a745;
-    font-weight: 500;
-}
-.modal-actions {
-    display: flex;
-    gap: 10px;
-    justify-content: flex-end;
-}
-</style>
-
 <div class="modal-overlay">
     <div class="modal-content">
         <div class="modal-header">
@@ -92,7 +16,7 @@
                 <div class="change-label">{{ field }}</div>
                 <div class="change-values">
                     <span class="old-value">{{ old_val or '(' + 'empty' + ')' }}</span>
-                    <span class="arrow">→</span>
+                    <span class="arrow"><i data-lucide="arrow-right"></i></span>
                     <span class="new-value">{{ new_val or '(' + 'empty' + ')' }}</span>
                 </div>
             </div>
@@ -105,12 +29,16 @@
 
         <div class="modal-actions">
             <button type="button" class="btn btn-outline" onclick="skipNotify()">{{ 'skip'|t }}</button>
-            <button type="button" class="btn btn-primary" onclick="notifyAttendees()">{{ 'notify_attendees_email'|t }}</button>
+            <button type="button" class="btn btn-primary" onclick="notifyAttendees()"><i data-lucide="mail"></i> {{ 'notify_attendees_email'|t }}</button>
         </div>
     </div>
 </div>
 
 <script>
+document.addEventListener('DOMContentLoaded', function() {
+    lucide.createIcons();
+});
+
 function notifyAttendees() {
     const changesText = `{% for field, old_val, new_val in changes %}{{ field }}: {{ old_val }} → {{ new_val }}
 {% endfor %}`.trim();