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/militaryAwareness.test.mjs

@@ -476,7 +476,7 @@ test('pending mapped installations render as unknown instead of a false zero', a
 // the dependencies reach it by different routes:
 //
 //   - ais-live-vessels is its REACHABLE producer. enable()/update() both resolve
-//     as soon as the first /api/ais-live poll answers, so the manager's
+//     as soon as the first /api/vessels poll answers, so the manager's
 //     lifecycle settles to `enabled` — but until the server-side socket delivers
 //     a position, firstConnectPhase stays 'loading' and the module reports busy,
 //     no lastUpdate, count 0, and an UNDEFINED status, so the status list alone