Round every heading readout through one shared helper

The transit, ALPR, vessel, CCTV and flight/military context fixes each
wrapped 359.5° to north with an inline Math.round(x) % 360. They now call
roundHeadingDegrees in src/data/headingDegrees.js, which also wraps negative
and multi-turn bearings. normalizeHeading moves there with it, and
cockpitMath re-exports it so existing imports keep working. It now adds a
turn only to a negative remainder, so a bearing just under half a degree
keeps its precision.

The awareness, Local ADS-B, cockpit wind, cockpit heading and Street Level
readouts use the same helper. The Cockpit's TRACK ACQUIRED signal rounded
without wrapping and could read COURSE 360°; it now uses
formatHeadingReadout, which shows --- for a track that is not finite.

src/ui/cctvPresentation.js

@@ -3,6 +3,7 @@ import { cctvSourceLabelText, cctvSourceMessageText } from './cctvFrames.js';
 
 import { createCctvVideoSurface } from './cctvVideo.js';
 import { presentCctvCalibration } from './cctvCalibration.js';
+import { roundHeadingDegrees } from '../data/headingDegrees.js';
 export function _calBadgeLabel(badge) {
   switch (badge) {
     case 'calibrated':
@@ -107,7 +108,7 @@ function metaText(state, enabled, activeCamera, catalogCount) {
         '{city} · HDG {heading} · FOV {fov} · RANGE {range}m · {projection}{calBadge} · {provider}{status}',
         {
           city: activeCamera.city,
-          heading: `${Math.round(activeCamera.headingDeg) % 360}°`,
+          heading: `${roundHeadingDegrees(Number(activeCamera.headingDeg)) ?? 0}°`,
           fov: `${Math.round(activeCamera.fovDeg)}°`,
           range: Math.round(activeCamera.rangeM),
           projection: projLabel,

src/ui/cockpitInstruments.js

@@ -120,7 +120,7 @@ export function updateHud(
     (tick) => formatAltitudeRulerTick(tick.valueFt),
   );
   view.heading = {
-    text: String(Math.round(heading) % 360).padStart(3, '0'),
+    text: formatHeadingReadout(heading),
     value: heading,
     immediate: forceContext,
   };

src/ui/cockpitPresentation.js

@@ -1,6 +1,10 @@
 /** Pure formatting and fixed presentation constants used by Cockpit components. */
 import { formatNumber, getLocale, isolate, t, msg } from '../i18n/index.js';
 import { formatQuantity } from './unitLabels.js';
+import {
+  normalizeHeading,
+  roundHeadingDegrees,
+} from '../data/headingDegrees.js';
 
 export const COCKPIT_HEADING_SLEW_DPS = 28;
 
@@ -135,8 +139,7 @@ export function cockpitUnitCase(text) {
 export function formatCockpitWindDirection(value) {
   if (!Number.isFinite(value)) return t('DIR UNKNOWN');
   const labels = Object.keys(COMPASS_POINT_LABELS);
-  const normalized = ((value % 360) + 360) % 360;
-  // 359.5° and above is north. Modulo keeps that from printing 360°.
-  const degrees = Math.round(normalized) % 360;
+  const normalized = normalizeHeading(value);
+  const degrees = roundHeadingDegrees(value);
   return `${compassPointLabel(labels[Math.round(normalized / 45) % labels.length])} · ${degrees}°`;
 }

src/ui/cockpitTrackingController.js

@@ -1,6 +1,7 @@
 /** Tracking identity, entry, exit and contact navigation for the Cockpit controller. */
 import { t } from '../i18n/index.js';
 import {
+  formatHeadingReadout,
   normalizeHeading,
   resolveTrackedAircraftInfo,
 } from '../cockpitMath.js';
@@ -186,9 +187,7 @@ export function enter() {
   this.startBriefRotation();
   const trackLabel =
     info.callsign || info.registration || info.icao24 || t('AIRCRAFT');
-  const trackHeading = String(
-    Math.round(normalizeHeading(info.track ?? 0)),
-  ).padStart(3, '0');
+  const trackHeading = formatHeadingReadout(info.track ?? 0);
   this.pushCockpitSignal(
     'track',
     'track',

src/ui/streetLevelPresentation.js

@@ -7,6 +7,7 @@ import {
   translateKnown,
 } from '../i18n/index.js';
 import { keyGuidanceText, keyRequirementText } from './keyGuidance.js';
+import { roundHeadingDegrees } from '../data/headingDegrees.js';
 
 // Street Level UI state to panel strings and flags. Pure, so it is testable.
 
@@ -175,9 +176,8 @@ function presentViewer(state) {
   const { street } = state;
   const right = [];
   if (street.isPano) right.push('360°');
-  // 359.5° and above rounds to north; modulo keeps it from printing 360°.
   if (Number.isFinite(street.bearing))
-    right.push(`${Math.round(street.bearing) % 360}°`);
+    right.push(`${roundHeadingDegrees(street.bearing)}°`);
   if (street.capturedAt)
     right.push(formatDate(street.capturedAt, street.capturedAtPrecision));
   const left = [];