feat: Add timezone setting in preferences + clickable logo

- Add timezone dropdown to settings modal with common timezones
- Save/load timezone preference per user
- Apply user's timezone preference after authentication
- Override system default with user preference if set
- Make dashboard logo clickable (returns to default filters)
- Show current timezone in settings

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

views/DashboardView.php

@@ -77,7 +77,7 @@
     </script>
     <div class="user-header">
         <div class="user-header-left">
-            <span class="app-title">🎫 Tinker Tickets</span>
+            <a href="/" class="app-title" style="text-decoration: none; color: inherit;">🎫 Tinker Tickets</a>
         </div>
         <div class="user-header-right">
             <?php if (isset($GLOBALS['currentUser'])): ?>
@@ -484,6 +484,29 @@
                             <option value="comfortable">Comfortable</option>
                         </select>
                     </div>
+
+                    <div class="setting-row">
+                        <label for="userTimezone">Timezone:</label>
+                        <select id="userTimezone" class="setting-select">
+                            <option value="America/New_York">Eastern (EST/EDT)</option>
+                            <option value="America/Chicago">Central (CST/CDT)</option>
+                            <option value="America/Denver">Mountain (MST/MDT)</option>
+                            <option value="America/Los_Angeles">Pacific (PST/PDT)</option>
+                            <option value="America/Anchorage">Alaska (AKST/AKDT)</option>
+                            <option value="Pacific/Honolulu">Hawaii (HST)</option>
+                            <option value="UTC">UTC</option>
+                            <option value="Europe/London">London (GMT/BST)</option>
+                            <option value="Europe/Paris">Paris (CET/CEST)</option>
+                            <option value="Europe/Berlin">Berlin (CET/CEST)</option>
+                            <option value="Asia/Tokyo">Tokyo (JST)</option>
+                            <option value="Asia/Shanghai">Shanghai (CST)</option>
+                            <option value="Asia/Kolkata">India (IST)</option>
+                            <option value="Australia/Sydney">Sydney (AEST/AEDT)</option>
+                        </select>
+                        <small style="color: var(--text-muted); margin-top: 0.25rem; display: block;">
+                            Current: <?php echo $GLOBALS['config']['TIMEZONE_ABBREV']; ?> (<?php echo $GLOBALS['config']['TIMEZONE']; ?>)
+                        </small>
+                    </div>
                 </div>
 
                 <!-- Notifications -->