Support panel hosts that serve the page from their own scheme

Codex serves panels from codex-sandbox:// pages, where origins are
opaque: the panel recognizes the app's own addresses by scheme and host,
the vessels feed resolves against the document address, and the dev
server answers Codex's sandbox origins with CORS.

src/standalone/layerSources.js

@@ -29,9 +29,9 @@ export function createStandaloneLayerSources() {
     military: createAdsbLolSource(),
     vessels: createAisStreamSource({
       apiUrl: import.meta.env?.VITE_AIS_LIVE_API_URL || '/api/ais-live',
-      // The app's server, also when a panel page loads the app under <base>.
-      origin: () =>
-        new URL(globalThis.document?.baseURI ?? 'http://localhost').origin,
+      // Resolved against the document's address, which a panel host may
+      // serve from its own scheme.
+      origin: () => globalThis.document?.baseURI ?? 'http://localhost',
     }),
     cctv: createCctvSource(),
     radio: createRadioSource(),