test: add suites for 8 simple state reducers + msgContent (+50)

Via subagent, all verified, no bugs:
- state/toast (7), room-list/roomList (6), inviteList (6), room-list/utils
  compareRoomsEqual (6), backupRestore (6), callEmbed dispose-on-replace (6),
  closedNavCategories factory + makeNavCategoryId (8).
- features/room/msgContent (5): getAudioMsgContent/getFileMsgContent incl.
  encrypted (content.file) vs plain (content.url) branch.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/state/toast.test.ts

@@ -0,0 +1,87 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { createStore } from 'jotai';
+import { toastQueueAtom, dismissToastAtom, ToastNotif } from './toast';
+
+// The queue lives in an unexported baseAtom; we drive the two write-only setters
+// (toastQueueAtom append + null no-op guard, dismissToastAtom remove-by-id)
+// through a jotai store and read back via toastQueueAtom's getter.
+
+const makeToast = (id: string): ToastNotif => ({
+  id,
+  displayName: `name-${id}`,
+  body: `body-${id}`,
+  roomName: `room-${id}`,
+  roomId: `!${id}:server`,
+});
+
+test('starts empty', () => {
+  const store = createStore();
+  assert.deepEqual(store.get(toastQueueAtom), []);
+});
+
+test('toastQueueAtom appends in order', () => {
+  const store = createStore();
+  const a = makeToast('a');
+  const b = makeToast('b');
+  store.set(toastQueueAtom, a);
+  store.set(toastQueueAtom, b);
+  assert.deepEqual(
+    store.get(toastQueueAtom).map((t) => t.id),
+    ['a', 'b'],
+  );
+  assert.equal(store.get(toastQueueAtom)[0], a);
+});
+
+test('toastQueueAtom ignores null (no-op guard)', () => {
+  const store = createStore();
+  store.set(toastQueueAtom, makeToast('a'));
+  store.set(toastQueueAtom, null);
+  assert.deepEqual(
+    store.get(toastQueueAtom).map((t) => t.id),
+    ['a'],
+  );
+});
+
+test('toastQueueAtom allows duplicate ids (no dedupe)', () => {
+  const store = createStore();
+  store.set(toastQueueAtom, makeToast('a'));
+  store.set(toastQueueAtom, makeToast('a'));
+  assert.equal(store.get(toastQueueAtom).length, 2);
+});
+
+test('dismissToastAtom removes the matching id only', () => {
+  const store = createStore();
+  store.set(toastQueueAtom, makeToast('a'));
+  store.set(toastQueueAtom, makeToast('b'));
+  store.set(toastQueueAtom, makeToast('c'));
+
+  store.set(dismissToastAtom, 'b');
+  assert.deepEqual(
+    store.get(toastQueueAtom).map((t) => t.id),
+    ['a', 'c'],
+  );
+});
+
+test('dismissToastAtom removes every entry sharing the id', () => {
+  const store = createStore();
+  store.set(toastQueueAtom, makeToast('a'));
+  store.set(toastQueueAtom, makeToast('a'));
+  store.set(toastQueueAtom, makeToast('b'));
+
+  store.set(dismissToastAtom, 'a');
+  assert.deepEqual(
+    store.get(toastQueueAtom).map((t) => t.id),
+    ['b'],
+  );
+});
+
+test('dismissToastAtom for an unknown id is a no-op', () => {
+  const store = createStore();
+  store.set(toastQueueAtom, makeToast('a'));
+  store.set(dismissToastAtom, 'missing');
+  assert.deepEqual(
+    store.get(toastQueueAtom).map((t) => t.id),
+    ['a'],
+  );
+});