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/value-sources.js

@@ -234,6 +234,22 @@ export async function editValueSource(sourceId) {
     }
 }
 
+// ── Clone ─────────────────────────────────────────────────────
+
+export async function cloneValueSource(sourceId) {
+    try {
+        const resp = await fetchWithAuth(`/value-sources/${sourceId}`);
+        if (!resp.ok) throw new Error('fetch failed');
+        const data = await resp.json();
+        delete data.id;
+        data.name = data.name + ' (copy)';
+        await showValueSourceModal(data);
+    } catch (e) {
+        if (e.isAuth) return;
+        showToast(e.message, 'error');
+    }
+}
+
 // ── Delete ────────────────────────────────────────────────────
 
 export async function deleteValueSource(sourceId) {
@@ -308,6 +324,7 @@ export function createValueSourceCard(src) {
             <div class="stream-card-props">${propsHtml}</div>
             ${src.description ? `<div class="template-config" style="opacity:0.7;">${escapeHtml(src.description)}</div>` : ''}
             <div class="template-card-actions">
+                <button class="btn btn-icon btn-secondary" onclick="cloneValueSource('${src.id}')" title="${t('common.clone')}">📋</button>
                 <button class="btn btn-icon btn-secondary" onclick="editValueSource('${src.id}')" title="${t('common.edit')}">✏️</button>
             </div>
         </div>