fix: watcher avatars, dependency TDS styling, asset versions, nav dropdown light theme

- watch_ticket.php GET now returns watcher list (up to 6 users) for avatar group
- TicketView: watcher avatar group rendered next to WATCH button, refreshes on toggle
- Rewrite renderDependencies/renderDependents to use TDS lt-kv-grid/lt-badge/lt-btn classes
- renderDependencies: show lt-alert--warning blocker banner when blocked_by has open tickets
- Fix ALL hardcoded ?v=20260327 asset version strings in CreateTicketView + all admin views
- base.css: fix .lt-nav-dropdown-menu hardcoded background → var(--bg-overlay)
- base.css: add light-theme overrides for nav dropdown menu (background, links, hover)
- ticket.css: add .lt-avatar-group and .lt-avatar--overflow styles for watcher display

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

views/admin/ApiKeysView.php

@@ -4,7 +4,8 @@ require_once __DIR__ . '/../../middleware/CsrfMiddleware.php';
 $nonce       = SecurityHeadersMiddleware::getNonce();
 $pageTitle   = 'API Keys';
 $activeNav   = 'admin-api-keys';
-$pageStyles  = ['/assets/css/dashboard.css?v=20260327'];
+$_v = $GLOBALS['config']['ASSET_VERSION'] ?? '1';
+$pageStyles  = ["/assets/css/dashboard.css?v={$_v}"];
 $pageScripts = ['/assets/js/keyboard-shortcuts.js'];
 include __DIR__ . '/../../views/layout_header.php';
 ?>