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>

assets/css/dashboard.css

@@ -4650,8 +4650,18 @@ table td:nth-child(4) {
     overflow-y: visible;
     margin: 0;
     padding: 0;
-    /* Subtle scroll hint via gradient on right edge */
     -webkit-overflow-scrolling: touch;
+    /* Scroll fade indicator: fades out right edge when content overflows */
+    background-image:
+        linear-gradient(to right, var(--bg-primary), var(--bg-primary)),
+        linear-gradient(to right, var(--bg-primary), var(--bg-primary)),
+        linear-gradient(to right, rgba(0,255,65,0.12), transparent),
+        linear-gradient(to left,  rgba(0,255,65,0.12), transparent);
+    background-position: left center, right center, left center, right center;
+    background-repeat: no-repeat;
+    background-color: var(--bg-primary);
+    background-size: 20px 100%, 20px 100%, 12px 100%, 12px 100%;
+    background-attachment: local, local, scroll, scroll;
 }
 
 @media (max-width: 768px) {

assets/js/ticket.js

@@ -548,10 +548,13 @@ function showTab(tabName) {
     });
 
     // Show selected tab and activate its button
-    document.getElementById(`${tabName}-tab`).style.display = 'block';
+    const tabEl = document.getElementById(`${tabName}-tab`);
+    if (tabEl) tabEl.style.display = 'block';
     const activeBtn = document.querySelector(`.tab-btn[data-tab="${tabName}"]`);
-    activeBtn.classList.add('active');
-    activeBtn.setAttribute('aria-selected', 'true');
+    if (activeBtn) {
+        activeBtn.classList.add('active');
+        activeBtn.setAttribute('aria-selected', 'true');
+    }
 
     // Load attachments when tab is shown
     if (tabName === 'attachments') {