UI/UX polish: terminal design system alignment pass

Views:
- DashboardView.php: remove hardcoded [ ] from admin-badge button (CSS adds them)
- DashboardView.php: view toggle ≡/▦ → [ = ]/[ # ] (view-btn suppresses auto-brackets)
- DashboardView.php: clear-search ✗ → [ X ] (plain text, no auto-brackets on <a>)
- DashboardView.php: remove ↓ arrow emoji from export button text
- TicketView.php: tab labels → UPPERCASE (tab-btn CSS adds [ ] around text)
- TicketView.php: Edit Ticket/Clone/Add Comment/Add → title-case → UPPERCASE
- TicketView.php: reply button ↩ → [ << ] (comment-action-btn has no auto-brackets)

JavaScript:
- dashboard.js: modal/action button text all → UPPERCASE (CONFIRM/CANCEL/SAVE/ASSIGN/UPDATE/DELETE PERMANENTLY)
- dashboard.js: null guard in loadTemplate(), toggleSelectAll()
- ticket.js: null guards in addDependency(), handleFileUpload()

CSS:
- dashboard.css: z-index 1001/1002 magic numbers → var(--z-modal)/var(--z-popover)
- ticket.css: status-select hover/focus border rgba(white) → terminal palette

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

assets/css/dashboard.css

@@ -5134,7 +5134,7 @@ table td:nth-child(4) {
         width: 85vw;
         max-width: 320px;
         height: 100vh;
-        z-index: 1001;
+        z-index: var(--z-modal);
         background: var(--bg-primary);
         transform: translateX(-100%);
         transition: transform 0.3s ease;
@@ -5636,7 +5636,7 @@ table td:nth-child(4) {
         max-height: 60vh;
         overflow-y: auto;
         border-radius: 0;
-        z-index: 1002;
+        z-index: var(--z-popover);
     }
 
     .admin-dropdown-content a {