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/layers/awareness/queries.js

@@ -35,7 +35,7 @@ export function createQueries({ state: layerState, services, parts, source }) {
     //     setInstallationStatus is only ever called with
     //     loading/zoom-in/ready/stale/empty/unavailable.
     //   - ais-live-vessels is what the predicate below is FOR. Its enable() and
-    //     update() both resolve as soon as the first /api/ais-live poll answers,
+    //     update() both resolve as soon as the first /api/vessels poll answers,
     //     so the lifecycle settles to `enabled` — but until the server-side socket
     //     delivers a position, firstConnectPhase is 'loading' and getStats()
     //     reports loading: true, lastUpdate: null, count 0, and an UNDEFINED