Animation None option, FPS min 1, serial COM lifecycle fixes

- Replace animation Enable checkbox with None option in effect selector;
  show effect description tooltip; disable speed slider when None selected
- Allow target FPS range 1-90 (was 10-90) across UI and backend validation
- Scope serial COM connections to target lifetime (no idle caching);
  use temporary connections for power-off/test mode
- Fix serial black frame on stop: flush after write, delay after task
  cancel to prevent race with in-flight thread pool write

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

server/src/wled_controller/templates/modals/target-editor.html

@@ -40,9 +40,9 @@
                         </label>
                         <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?">?</button>
                     </div>
-                    <small class="input-hint" style="display:none" data-i18n="targets.fps.hint">How many frames per second to send to the device (10-90). Higher values give smoother animations but use more bandwidth.</small>
+                    <small class="input-hint" style="display:none" data-i18n="targets.fps.hint">How many frames per second to send to the device (1-90). Higher values give smoother animations but use more bandwidth.</small>
                     <div class="slider-row">
-                        <input type="range" id="target-editor-fps" min="10" max="90" value="30" oninput="document.getElementById('target-editor-fps-value').textContent = this.value">
+                        <input type="range" id="target-editor-fps" min="1" max="90" value="30" oninput="document.getElementById('target-editor-fps-value').textContent = this.value">
                         <span class="slider-value">fps</span>
                     </div>
                 </div>