fix(vessels): show a 359.7° course as 0°, not 360°

Vessel cards and the AIS HUD rounded the direction without wrapping, so
a vessel reporting no heading and a course over ground of 359.5° or more
read "360°" on its cards and "HDG: 360DEG" in the HUD. The rounded
direction now wraps to 0°.

src/layers/vessels/cards.js

@@ -60,7 +60,10 @@ export function createCards({
     if (record.speed !== null && record.speed !== undefined)
       parts.push(formatSpeed(record.speed));
     const direction = record.heading ?? record.course;
-    if (Number.isFinite(direction)) parts.push(`${Math.round(direction)}°`);
+    // A course of 359.5° and above rounds to north; modulo keeps it from
+    // printing 360°. The selected card and the HUD wrap the same way.
+    if (Number.isFinite(direction))
+      parts.push(`${Math.round(direction) % 360}°`);
     return {
       id: vesselOverlayEntryId(record),
       actionable: Boolean(record?.mmsi),
@@ -91,7 +94,7 @@ export function createCards({
       [
         vesselTypeShort(record) || t('VESSEL'),
         formatSpeed(record.speed),
-        Number.isFinite(direction) ? `${Math.round(direction)}°` : '--°',
+        Number.isFinite(direction) ? `${Math.round(direction) % 360}°` : '--°',
       ].join(' · '),
     ];
     const destination = String(record.destination || '').trim();
@@ -181,7 +184,7 @@ export function createCards({
 
   function formatHeading(heading) {
     return t('{heading}DEG', {
-      heading: Number.isFinite(heading) ? Math.round(heading) : '--',
+      heading: Number.isFinite(heading) ? Math.round(heading) % 360 : '--',
     });
   }