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/style.css

@@ -629,6 +629,15 @@ section {
     text-decoration: underline;
 }
 
+ul.section-tip {
+    list-style: disc;
+    padding-left: 28px;
+}
+
+ul.section-tip li {
+    margin: 2px 0;
+}
+
 .form-group {
     margin-bottom: 15px;
 }