fix(assets): reference logo/favicon PNGs by URL instead of importing from public/

Importing images from public/ (`import X from '../../public/res/*.png'`) is
fragile under Vite with `publicDir: false` and can white-screen the dev app —
Vite tries to resolve the public/ path as a module. Switch the five logo/
favicon call sites to the repo's existing BASE_URL URL pattern
(`${trimTrailingSlash(import.meta.env.BASE_URL)}/public/res/...`), matching how
config.json, locales, and the Element Call widget are referenced. Resolves
identically in dev and the static-copied prod build (public/res -> dist/public/res).

Sounds under public/sound/ stay ESM-imported: that folder is not copied to
dist/ by vite-plugin-static-copy, so a URL reference would 404.

Also add a Local Development section to the README (no-backend model, npm ci /
npm start on :8080, which homeserver to log in against, OIDC-on-localhost note).

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

src/app/features/settings/about/About.tsx

@@ -4,11 +4,13 @@ import { Page, PageContent, PageHeader } from '../../../components/page';
 import { SequenceCard } from '../../../components/sequence-card';
 import { SequenceCardStyle } from '../styles.css';
 import { SettingTile } from '../../../components/setting-tile';
-import LotusLogo from '../../../../../public/res/Lotus.png';
+import { trimTrailingSlash } from '../../../utils/common';
 import pkg from '../../../../../package.json';
 import { clearCacheAndReload } from '../../../../client/initMatrix';
 import { useMatrixClient } from '../../../hooks/useMatrixClient';
 
+const LotusLogo = `${trimTrailingSlash(import.meta.env.BASE_URL)}/public/res/Lotus.png`;
+
 type MSC1929Contact = {
   matrix_id?: string;
   email_address?: string;

src/app/pages/auth/AuthLayout.tsx

@@ -20,7 +20,7 @@ import {
 } from '../../hooks/useClientConfig';
 import { AsyncStatus, useAsyncCallback } from '../../hooks/useAsyncCallback';
 import { LOGIN_PATH, REGISTER_PATH, RESET_PASSWORD_PATH } from '../paths';
-import LotusLogo from '../../../../public/res/Lotus.png';
+import { trimTrailingSlash } from '../../utils/common';
 import { ServerPicker } from './ServerPicker';
 import { AutoDiscoveryAction, autoDiscovery } from '../../cs-api';
 import { SpecVersionsLoader } from '../../components/SpecVersionsLoader';
@@ -31,6 +31,8 @@ import { AuthFlowsProvider } from '../../hooks/useAuthFlows';
 import { AuthServerProvider } from '../../hooks/useAuthServer';
 import { tryDecodeURIComponent } from '../../utils/dom';
 
+const LotusLogo = `${trimTrailingSlash(import.meta.env.BASE_URL)}/public/res/Lotus.png`;
+
 const currentAuthPath = (pathname: string): string => {
   if (matchPath(LOGIN_PATH, pathname)) {
     return LOGIN_PATH;

src/app/pages/auth/oidc/oidcConfig.ts

@@ -1,8 +1,10 @@
 import type { OidcRegistrationClientMetadata } from 'matrix-js-sdk';
-import LotusLogo from '../../../../../public/res/Lotus.png';
+import { trimTrailingSlash } from '../../../utils/common';
 import { OIDC_CALLBACK_PATH } from '../../paths';
 import { getOriginBaseUrl, withOriginBaseUrl } from '../../pathUtils';
 
+const LotusLogo = `${trimTrailingSlash(import.meta.env.BASE_URL)}/public/res/Lotus.png`;
+
 /**
  * Absolute URL the OIDC provider redirects back to after authorization.
  *

src/app/pages/client/ClientNonUIFeatures.tsx

@@ -17,9 +17,7 @@ import { manualDndAtom } from '../../state/manualDnd';
 import { isSnoozeActive, notificationSnoozeUntilAtom } from '../../state/notificationSnooze';
 import { isWithinTimeWindow } from '../../utils/timeWindow';
 import { roomToUnreadAtom } from '../../state/room/roomToUnread';
-import LogoSVG from '../../../../public/res/lotus.png';
-import LogoUnreadSVG from '../../../../public/res/lotus-unread.png';
-import LogoHighlightSVG from '../../../../public/res/lotus-highlight.png';
+import { trimTrailingSlash } from '../../utils/common';
 import NotificationSound from '../../../../public/sound/notification.ogg';
 import InviteSound from '../../../../public/sound/invite.ogg';
 import { notificationPermission, setFavicon, showOsNotification } from '../../utils/dom';
@@ -69,6 +67,10 @@ import {
 
 // Grace period after the initial sync settles before invite notifications arm, so
 // the async invite-atom population lands first and isn't mistaken for new invites.
+const LogoSVG = `${trimTrailingSlash(import.meta.env.BASE_URL)}/public/res/lotus.png`;
+const LogoUnreadSVG = `${trimTrailingSlash(import.meta.env.BASE_URL)}/public/res/lotus-unread.png`;
+const LogoHighlightSVG = `${trimTrailingSlash(import.meta.env.BASE_URL)}/public/res/lotus-highlight.png`;
+
 const INVITE_NOTIFY_ARM_DELAY_MS = 3000;
 
 function SystemEmojiFeature() {

src/app/pages/client/WelcomePage.tsx

@@ -1,9 +1,11 @@
 import React from 'react';
 import { Box, Button, Icon, Icons, Text, config, toRem } from 'folds';
 import { Page, PageHero, PageHeroSection } from '../../components/page';
-import LotusLogo from '../../../../public/res/Lotus.png';
+import { trimTrailingSlash } from '../../utils/common';
 import pkg from '../../../../package.json';
 
+const LotusLogo = `${trimTrailingSlash(import.meta.env.BASE_URL)}/public/res/Lotus.png`;
+
 export function WelcomePage() {
   return (
     <Page>