fix(transit): show a reported 359.6° bearing as hdg 0°, not hdg 360°

The selected-vehicle card rounded the operator's reported bearing without
wrapping, so a GTFS-Realtime vehicle heading 359.5° or more read
"reported hdg 360°". The card now wraps after rounding: 359.6° reads
"reported hdg 0°", 359.4° still reads "reported hdg 359°".

docs/CURRENT-STATE.md

@@ -4347,7 +4347,9 @@ to 0.45 at two minutes, 0.20 at ten minutes and 0.08 at fifteen minutes.
 display delay and newest-report age, reported speed/stop, vehicle ID, and
 available trail duration. Report age is rounded to whole seconds and stays in seconds while that rounded
 count is below 90; otherwise it shows completed minutes calculated from the
-rounded second count. Its anchor follows the rendered marker; text is
+rounded second count. The reported heading wraps after rounding to whole
+degrees, so a bearing of 359.5° or more reads `hdg 0°` rather than `hdg 360°`.
+Its anchor follows the rendered marker; text is
 checked at 4 Hz and published when it changes. DETECT labels retain route,
 mode and motion, with the selected label suppressed beside its fuller card.
 Candidate membership changes on revisions, coalesced at 4 Hz; paints read