Fix DXcam engine and improve UI: loading spinners, template card gap

DXcam engine overhaul:
- Remove all user-facing config (device_idx, output_idx, output_color)
  since these are auto-resolved or hardcoded to RGB
- Use one-shot grab() mode with retry for reliability
- Lazily create camera per display via _ensure_camera()
- Clear dxcam global factory cache to prevent stale DXGI state

UI improvements:
- Replace "Loading..." text with CSS spinner animations
- Fix template card header gap on default cards (scope padding-right
  to cards with remove button only via :has selector)
- Add auto-restart server rule to CLAUDE.md

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

server/src/wled_controller/static/index.html

@@ -49,14 +49,14 @@
                     <span data-i18n="devices.wled_note2">This controller sends pixel color data and controls brightness per device.</span>
                 </p>
                 <div id="devices-list" class="devices-grid">
-                    <div class="loading" data-i18n="devices.loading">Loading devices...</div>
+                    <div class="loading-spinner"></div>
                 </div>
             </div>
 
             <div class="tab-panel" id="tab-displays">
                 <div class="display-layout-preview">
                     <div id="display-layout-canvas" class="display-layout-canvas">
-                        <div class="loading" data-i18n="displays.loading">Loading layout...</div>
+                        <div class="loading-spinner"></div>
                     </div>
                 </div>
                 <div id="displays-list" style="display: none;"></div>
@@ -69,7 +69,7 @@
                     </span>
                 </p>
                 <div id="templates-list" class="templates-grid">
-                    <div class="loading" data-i18n="templates.loading">Loading templates...</div>
+                    <div class="loading-spinner"></div>
                 </div>
             </div>
         </div>