feat: add notifications_enabled toggle for users (web + Android)

views/auth/profile.php

@@ -54,6 +54,18 @@
                 </div>
             </div>
 
+            <div class="form-section">
+                <h3>Notification Preferences</h3>
+                <label class="checkbox-label">
+                    <input type="checkbox" name="notifications_enabled" value="1"
+                           <?= ($user['notifications_enabled'] ?? 1) ? 'checked' : '' ?>>
+                    Enable push notifications
+                </label>
+                <p style="color:var(--text-muted);font-size:0.85em;margin:4px 0 0 24px">
+                    Receive alerts for threshold breaches and app updates.
+                </p>
+            </div>
+
             <div class="form-actions">
                 <button type="submit" class="btn btn-primary">
                     <i class="fas fa-save"></i> Update Profile