Add target FPS slider to Capture Settings and remove unused HACS workflow

- Add Target FPS slider (range 10-90) to Capture Settings dialog
- Fix settings PUT to merge with current values instead of resetting defaults
- Update FPS validation range to 10-90 in schema and config
- Remove irrelevant .github/workflows/validate.yml (HACS leftover)

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

server/src/wled_controller/static/index.html

@@ -261,6 +261,15 @@
                         <small class="input-hint" data-i18n="settings.display_index.hint">Which screen to capture for this device</small>
                     </div>
 
+                    <div class="form-group">
+                        <label for="capture-settings-fps" data-i18n="settings.fps">Target FPS:</label>
+                        <div class="slider-row">
+                            <input type="range" id="capture-settings-fps" min="10" max="90" value="30" oninput="document.getElementById('capture-settings-fps-value').textContent = this.value">
+                            <span id="capture-settings-fps-value" class="slider-value">30</span>
+                        </div>
+                        <small class="input-hint" data-i18n="settings.fps.hint">Target frames per second (10-90)</small>
+                    </div>
+
                     <div class="form-group">
                         <label for="capture-settings-template" data-i18n="settings.capture_template">Capture Template:</label>
                         <select id="capture-settings-template"></select>