Add clone buttons, fix card navigation highlight, UI polish

- Add clone buttons to Audio Source and Value Source cards
- Fix command palette navigation destroying card highlight by skipping
  redundant data reload (skipLoad option on switchTab)
- Convert value source modal sliders to value-in-label pattern
- Change audio/value source modal footers to icon-only buttons
- Remove separator lines between card sections
- Add UI conventions to CLAUDE.md (card appearance, modal footer, sliders)

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

server/src/wled_controller/static/js/features/tabs.js

@@ -20,7 +20,7 @@ function _setHash(tab, subTab) {
 
 let _suppressHashUpdate = false;
 
-export function switchTab(name, { updateHash = true } = {}) {
+export function switchTab(name, { updateHash = true, skipLoad = false } = {}) {
     document.querySelectorAll('.tab-btn').forEach(btn => {
         const isActive = btn.dataset.tab === name;
         btn.classList.toggle('active', isActive);
@@ -40,11 +40,11 @@ export function switchTab(name, { updateHash = true } = {}) {
 
     if (name === 'dashboard') {
         // Use window.* to avoid circular imports with feature modules
-        if (apiKey && typeof window.loadDashboard === 'function') window.loadDashboard();
+        if (!skipLoad && apiKey && typeof window.loadDashboard === 'function') window.loadDashboard();
     } else {
         if (typeof window.stopPerfPolling === 'function') window.stopPerfPolling();
         if (typeof window.stopUptimeTimer === 'function') window.stopUptimeTimer();
-        if (!apiKey) return;
+        if (!apiKey || skipLoad) return;
         if (name === 'streams') {
             if (typeof window.loadPictureSources === 'function') window.loadPictureSources();
         } else if (name === 'targets') {