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/standalone/layerSources.js

@@ -1,8 +1,8 @@
 import { createOpenFreeMapSource } from '../sources/openFreeMap.js';
 import {
-  createOpenSkySource,
-  createAdsbLolSource,
-  createAisStreamSource,
+  createFlightSource,
+  createMilitarySource,
+  createVesselSource,
 } from '../sources/live/standalone.js';
 import { createCctvSource } from '../layers/cctv/source.js';
 import { createRadioSource } from '../layers/radio/source.js';
@@ -25,10 +25,10 @@ export function createStandaloneLayerSources() {
   const mapTiles = createOpenFreeMapSource();
   return {
     ...createReferenceSources(),
-    flights: createOpenSkySource(),
-    military: createAdsbLolSource(),
-    vessels: createAisStreamSource({
-      apiUrl: import.meta.env?.VITE_AIS_LIVE_API_URL || '/api/ais-live',
+    flights: createFlightSource(),
+    military: createMilitarySource(),
+    vessels: createVesselSource({
+      apiUrl: import.meta.env?.VITE_AIS_LIVE_API_URL || '/api/vessels',
       // Resolved against the document's address, which a panel host may
       // serve from its own scheme.
       origin: () => globalThis.document?.baseURI ?? 'http://localhost',