feat: name live feed routes and sources for what they serve

The flight, military and vessel feeds were named after the providers the
bundled server uses (/api/opensky, /api/adsblol/mil, /api/ais-live and
their track routes; createOpenSkySource, createAdsbLolSource,
createAisStreamSource). Any server should be able to answer a feed from
its own provider, so the feeds are now:

  /api/flights   /api/flights/track?icao24=
  /api/military  /api/military/track?hex=
  /api/vessels   /api/vessels/track?mmsi=

with createFlightSource, createMilitarySource and createVesselSource. The
old routes are removed. Each server names its provider in X-Feed-Source
(the bundled server sends OpenSky Network, adsb.lol and AISStream, so its
attribution is unchanged) and the military feed's cache state and age in
X-Feed-Cache and X-Feed-Age-Ms. Sources report the provider the server
names and fall back to the feed's name.

src/data/aisLiveVessels.test.mjs

@@ -1668,7 +1668,7 @@ test('a vessel analyst record carries the MMSI the tracker keys on', () => {
 });
 
 test('vessel selection passes the opaque source reference to optional history', async () => {
-  const { createAisStreamSource } = await import('../sources/live/standalone.js');
+  const { createVesselSource } = await import('../sources/live/standalone.js');
   _setVesselStateForTest({ enabled: false });
   const requests = [];
   aisLiveVesselsLayer.setSource({
@@ -1688,6 +1688,6 @@ test('vessel selection passes the opaque source reference to optional history',
   } finally {
     harness.cleanup();
     _setVesselStateForTest({ enabled: false });
-    aisLiveVesselsLayer.setSource(createAisStreamSource());
+    aisLiveVesselsLayer.setSource(createVesselSource());
   }
 });