fix(rail): Montpellier tram speeds are converted from km/h

TaM publishes km/h where GTFS-Realtime asks m/s, and the Transit layer's
entry for the same feed already sets speedUnit: 'km/h'. The Rail entry did
not, so the proxy passed the readings through and the card multiplied them
by 3.6 again: a tram at 30 km/h read about 108 km/h. A registry test now
requires a Rail feed that Transit also reads to declare the same unit.

src/data/railFeeds.js

@@ -476,7 +476,9 @@ const OWNER_AUTHORIZED_NO_TERMS =
  * 64 MiB: railMaxBodyBytes; the feeds that set one publish small documents
  * and set a lower cap), and `headerClock: 'untrusted'` marks a feed whose
  * header time is wrong and whose vehicles carry none: every train is then
- * stamped with the fetch time.
+ * stamped with the fetch time. `speedUnit: 'km/h'` marks a feed that
+ * publishes km/h where the spec requires m/s; the proxy converts it, as for
+ * Transit (src/data/transitFeeds.js).
  * `tripUpdatesUrl` is the operator's GTFS-RT TripUpdates feed, served as
  * `/api/rail/updates/<id>`.
  *
@@ -509,6 +511,7 @@ const OWNER_AUTHORIZED_NO_TERMS =
  *   url: string,
  *   positions?: 'gps'|'event',
  *   headers?: Record<string, string>, headerClock?: 'untrusted',
+ *   speedUnit?: 'km/h',
  *   pollIntervalMs?: number, tripUpdatesUrl?: string,
  *   tripUpdatesIntervalMs?: number, maxBodyBytes?: number,
  *   limits?: {quote: string, note?: string},
@@ -1307,6 +1310,10 @@ export const RAIL_FEED_REGISTRY = Object.freeze([
     format: 'gtfs-rt',
     // Every TaM vehicle (about 15 KB); the tram routes are kept.
     url: 'https://gtfsproxy.e-tam.fr/COMMON/VehiclePosition.pb',
+    // Speeds are km/h where the spec asks m/s (the Transit layer's entry for
+    // this feed measured readings at 3.3 times the movement); the proxy
+    // converts them.
+    speedUnit: 'km/h',
     tripUpdatesUrl: 'https://gtfsproxy.e-tam.fr/COMMON/TripUpdate.pb',
     tripUpdatesIntervalMs: 60_000,
     staticGtfsUrl: 'https://gtfsproxy.e-tam.fr/COMMON/GTFS.zip',

src/data/railFeeds.test.mjs

@@ -66,6 +66,7 @@ const REGISTRY_FIELDS = new Set([
   'positions',
   'headers',
   'headerClock',
+  'speedUnit',
   'pollIntervalMs',
   'tripUpdatesUrl',
   'tripUpdatesIntervalMs',
@@ -472,3 +473,19 @@ test('feeds that read routes from their schedule pack can build one', () => {
     }))
       assert.ok(!/@/.test(value), feed.id);
 });
+
+test('a feed Transit also reads declares the same speed unit', async () => {
+  const { TRANSIT_FEED_REGISTRY } = await import('./transitFeeds.js');
+  const transitByUrl = new Map(
+    TRANSIT_FEED_REGISTRY.map((feed) => [feed.url, feed]),
+  );
+  let shared = 0;
+  for (const feed of RAIL_FEED_REGISTRY) {
+    const transit = transitByUrl.get(feed.url);
+    if (!transit) continue;
+    shared += 1;
+    assert.equal(feed.speedUnit, transit.speedUnit, feed.id);
+  }
+  assert.ok(shared > 0);
+  assert.equal(getRegisteredRailFeed('tam-montpellier').speedUnit, 'km/h');
+});