feat: nano-style footer bar, missing utility classes, CSS semantic vars

- layout_footer.php: add lt-footer with context-sensitive keyboard hint bar
  ([ ~ ] HOME | [ / ] SEARCH | [ + ] NEW | [ * ] CFG | [ ? ] HELP)
  Context adapts for dashboard, ticket, and admin pages
- layout_footer.php: wire show-keyboard-help and open-settings for all pages
- base.css: body { display:flex; flex-direction:column } + lt-main { flex:1 }
  so footer sticks to bottom of viewport on short pages
- base.css: add lt-flex-gap-xs/sm/md/lg and lt-flex-align-start/center/end
  (were used across all views but never defined — causing broken layouts)
- base.css: add --lt-danger/amber/cyan/success/text-primary CSS variables
  (referenced in ticket.css and dashboard.css fallbacks but never declared)
- base.css: add lt-text-danger/warning/success/info/primary utility classes
  (used in TicketView, DashboardView, admin views but not defined in base.css)
- DashboardView.php: remove ascii-banner.js (loaded but never called)
- TemplatesView.php: fix priority badge from lt-p* to lt-chip component

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

views/DashboardView.php

@@ -16,7 +16,6 @@ $pageTitle  = 'Dashboard';
 $activeNav  = 'dashboard';
 $pageStyles = ['/assets/css/dashboard.css?v=20260327'];
 $pageScripts = [
-    '/assets/js/ascii-banner.js?v=20260327',
     '/assets/js/markdown.js?v=20260327',
     '/assets/js/dashboard.js?v=20260327',
     '/assets/js/advanced-search.js?v=20260327',