Prioritize round-number ticks, add calibration tip list with i18n

Tick labels: round-number ticks (300, 900, etc.) now take priority over
edge boundary labels (288, 933). When they overlap, the boundary label
is suppressed but its tick line is preserved.

Calibration tips: convert single paragraph to bulleted list with
individual i18n keys, add tip about toggling edge inputs.

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

server/src/wled_controller/static/index.html

@@ -84,7 +84,13 @@
             </div>
             <div class="modal-body">
                 <input type="hidden" id="calibration-device-id">
-                <p class="section-tip" data-i18n="calibration.preview.click_hint">Click an edge to toggle test LEDs on/off</p>
+                <ul class="section-tip">
+                    <li data-i18n="calibration.tip.led_count">Enter LED count per edge</li>
+                    <li data-i18n="calibration.tip.start_corner">Click a corner to set the start position</li>
+                    <li data-i18n="calibration.tip.span">Drag green bars to adjust coverage span</li>
+                    <li data-i18n="calibration.tip.test">Click an edge to toggle test LEDs</li>
+                    <li data-i18n="calibration.tip.toggle_inputs">Click total LED count to toggle edge inputs</li>
+                </ul>
                 <!-- Interactive Preview with integrated LED inputs and test toggles -->
                 <div style="margin-bottom: 12px; padding: 0 24px;">
                     <div class="calibration-preview">