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/streams.js

@@ -748,6 +748,7 @@ function renderPictureSourcesList(streams) {
                 <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="cloneAudioSource('${src.id}')" title="${t('common.clone')}">📋</button>
                     <button class="btn btn-icon btn-secondary" onclick="editAudioSource('${src.id}')" title="${t('common.edit')}">✏️</button>
                 </div>
             </div>