Take TTC vehicle mode from the fleet number before the route

Replacement buses on 5xx streetcar routes were drawn as streetcars, and
Flexity streetcars reporting no route were drawn as buses. A feed can now
supply vehicleMode(id); TTC maps 4400-4699 to streetcars and every other
fleet number to buses, falling back to the route otherwise.

src/data/transitFeeds.test.mjs

@@ -279,6 +279,22 @@ test('TTC route numbers tell a streetcar from a bus', () => {
   );
 });
 
+test('a TTC fleet number outranks the route', () => {
+  // Buses replace streetcars on 5xx routes during track work, and streetcars
+  // out of service report no route; the Flexity fleet is 4400–4699.
+  const ttc = getTransitFeed('ttc-toronto');
+  assert.equal(transitModeFor(ttc, '506', '8515'), 'bus');
+  assert.equal(transitModeFor(ttc, '512', '3101'), 'bus');
+  assert.equal(transitModeFor(ttc, null, '4507'), 'tram');
+  assert.equal(transitModeResolved(ttc, null, '4507'), true);
+  assert.equal(transitModeFor(ttc, '504', '4400'), 'tram');
+  assert.equal(transitModeFor(ttc, '29', '4699'), 'tram');
+  assert.equal(transitModeFor(ttc, '501', '4700'), 'bus');
+  // A vehicle id that is not a fleet number leaves the route to decide.
+  assert.equal(transitModeFor(ttc, '501', 'abc'), 'tram');
+  assert.equal(transitModeFor(ttc, '501'), 'tram');
+});
+
 test('the TTC row records that BusTime carries no subway', () => {
   const sources = readFileSync(
     new URL('../../DATA_SOURCES.md', import.meta.url),