feat: add per-layer LED range and collapsible layers to composite source

Composite layers now support optional start/end LED range (toggleable)
and reverse flag, making composite a superset of mapped source. Layers
are collapsible with animated expand/collapse and consistent 0.85rem
font sizing. Delete button restyled as ghost icon button.

Also includes minor dashboard CSS overflow fixes.

server/src/wled_controller/static/js/features/dashboard.ts

@@ -598,7 +598,7 @@ function renderDashboardTarget(target: any, isRunning: boolean, devicesMap: Reco
             <div class="dashboard-target-info">
                 <span class="dashboard-target-icon">${icon}</span>
                 <div>
-                    <div class="dashboard-target-name">${escapeHtml(target.name)}${healthDot}</div>
+                    <div class="dashboard-target-name"><span class="dashboard-target-name-text">${escapeHtml(target.name)}</span>${healthDot}</div>
                     ${subtitleParts.length ? `<div class="dashboard-target-subtitle">${escapeHtml(subtitleParts.join(' · '))}</div>` : ''}
                 </div>
             </div>