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>

CLAUDE.md

@@ -149,6 +149,38 @@ Every editor modal **must** have a dirty check so closing with unsaved changes s
 
 The base class handles: `isDirty()` comparison, confirmation dialog, backdrop click, ESC key, focus trapping, and body scroll lock.
 
+### Card appearance
+
+When creating or modifying entity cards (devices, targets, CSS sources, streams, audio/value sources, templates), **always reference existing cards** of the same or similar type for visual consistency. Cards should have:
+
+- Clone (📋) and Edit (✏️) icon buttons in `.template-card-actions`
+- Delete (✕) button as `.card-remove-btn`
+- Property badges in `.stream-card-props` with emoji icons
+
+### Modal footer buttons
+
+Use **icon-only** buttons (✓ / ✕) matching the device settings modal pattern, **not** text buttons:
+
+```html
+<div class="modal-footer">
+    <button class="btn btn-icon btn-secondary" onclick="closeMyModal()" title="Cancel" data-i18n-title="settings.button.cancel" data-i18n-aria-label="aria.cancel">&#x2715;</button>
+    <button class="btn btn-icon btn-primary" onclick="saveMyEntity()" title="Save" data-i18n-title="settings.button.save" data-i18n-aria-label="aria.save">&#x2713;</button>
+</div>
+```
+
+### Slider value display
+
+For range sliders, display the current value **inside the label** (not in a separate wrapper). This keeps the value visible next to the property name:
+
+```html
+<label for="my-slider"><span data-i18n="my.label">Speed:</span> <span id="my-slider-display">1.0</span></label>
+...
+<input type="range" id="my-slider" min="0" max="10" step="0.1" value="1.0"
+    oninput="document.getElementById('my-slider-display').textContent = this.value">
+```
+
+Do **not** use a `range-with-value` wrapper div.
+
 ## General Guidelines
 
 - Always test changes before marking as complete