Move ASCII banner into boot sequence, fix remaining UI issues

- Remove collapsible ASCII banner from dashboard (was cluttering the UI)
- Show ASCII banner in the boot overlay on first session visit, above
  the boot messages, with a 400ms pause before messages begin
- Add scroll fade indicator (green-tinted gradient edges) to .table-wrapper
  so users can see when the table is horizontally scrollable
- Fix null guards for tab switcher in ticket.js (tabEl, activeBtn)
- Fix Reset → RESET uppercase in AuditLogView and UserActivityView

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

views/admin/AuditLogView.php

@@ -78,7 +78,7 @@ $nonce = SecurityHeadersMiddleware::getNonce();
                     </div>
                     <div style="display: flex; align-items: flex-end;">
                         <button type="submit" class="btn">FILTER</button>
-                        <a href="?" class="btn btn-secondary" style="margin-left: 0.5rem;">Reset</a>
+                        <a href="?" class="btn btn-secondary" style="margin-left: 0.5rem;">RESET</a>
                     </div>
                 </form>