Simplify local transport code

As of the removal of 'Legacy' mode, there can no longer be a difference between the transport you advertise in your membership and the transport you publish media on, so the local transport code can be simplified considerably. For instance, the function which gets the local transport can simply return a promise rather than being reactive.

I kept the local transport as an Observable in other modules so that they could easily be tested with existing marble tests.

src/utils/observable.test.ts

@@ -9,30 +9,9 @@ import { expect, test } from "vitest";
 import { type Observable, of, Subject, switchMap } from "rxjs";
 
 import { withTestScheduler } from "./test";
-import { or$, filterBehavior, generateItems, pauseWhen } from "./observable";
+import { filterBehavior, generateItems, pauseWhen } from "./observable";
 import { type Behavior } from "../state/Behavior";
 
-const yesNo = {
-  y: true,
-  n: false,
-};
-
-test("or$", () => {
-  withTestScheduler(({ behavior, expectObservable }) => {
-    const input1Marbles = "ny--n--";
-    const input2Marbles = "n-y--n-";
-    const input3Marbles = "n--y--n";
-    const outputMarbles = "nyyyyyn";
-    expectObservable(
-      or$(
-        behavior(input1Marbles, yesNo),
-        behavior(input2Marbles, yesNo),
-        behavior(input3Marbles, yesNo),
-      ),
-    ).toBe(outputMarbles, yesNo);
-  });
-});
-
 test("pauseWhen", () => {
   withTestScheduler(({ behavior, expectObservable }) => {
     const inputMarbles = " abcdefgh-i-jk-";

src/utils/observable.ts

@@ -8,7 +8,6 @@ Please see LICENSE in the repository root for full details.
 import {
   type Observable,
   audit,
-  combineLatest,
   concat,
   defer,
   filter,
@@ -113,14 +112,6 @@ export function getValue<T>(state$: Observable<T>): T {
   return value;
 }
 
-/**
- * Creates an Observable that has a value of true whenever some of its inputs
- * are true.
- */
-export function or$(...inputs: Observable<boolean>[]): Observable<boolean> {
-  return combineLatest(inputs, (...flags) => flags.some((flag) => flag));
-}
-
 /**
  * RxJS operator that pauses all changes in the input value whenever a Behavior
  * is true. When the Behavior returns to being false, the most recently