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>

assets/css/ticket.css

@@ -270,6 +270,26 @@ kbd {
   .thread-depth-3 { margin-left: 2.25rem; }
 }
 
+/* ── Watcher avatar group in toolbar ────────────────────────── */
+.lt-avatar-group {
+  display: flex;
+  align-items: center;
+}
+.lt-avatar-group .lt-avatar {
+  margin-left: -0.4rem;
+  border: 1px solid var(--bg-primary, #030508);
+  flex-shrink: 0;
+}
+.lt-avatar-group .lt-avatar:first-child { margin-left: 0; }
+.lt-avatar--overflow {
+  background: var(--bg-tertiary, #1a1f2e);
+  border: 1px solid var(--border-dim, rgba(0,255,65,0.2)) !important;
+  font-size: 0.55rem;
+  font-weight: 700;
+  color: var(--text-muted);
+  cursor: default;
+}
+
 /* ── Description read view ───────────────────────────────────── */
 /* Shown in read mode instead of a disabled (faded) textarea.     */
 /* Uses lt-markdown typography for full contrast on dark/OLED.    */