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,