Fix RTL layout in debug log and other popup windows

ts/util/setDocumentLocale.dom.ts

@@ -0,0 +1,14 @@
+// Copyright 2026 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+export function setDocumentLocale(document: Document): void {
+  document.documentElement.setAttribute(
+    'lang',
+    window.SignalContext.getResolvedMessagesLocale().split(/[-_]/)[0]
+  );
+
+  document.documentElement.setAttribute(
+    'dir',
+    window.SignalContext.getResolvedMessagesLocaleDirection()
+  );
+}

ts/windows/about/app.dom.tsx

@@ -7,10 +7,13 @@ import '../sandboxedInit.dom.ts';
 import { About } from '../../components/About.dom.tsx';
 import { strictAssert } from '../../util/assert.std.ts';
 import { AppProvider } from '../AppProvider.dom.tsx';
+import { setDocumentLocale } from '../../util/setDocumentLocale.dom.ts';
 
 const { AboutWindowProps } = window.Signal;
 const { i18n } = window.SignalContext;
 
+setDocumentLocale(document);
+
 strictAssert(AboutWindowProps, 'window values not provided');
 
 const app = document.getElementById('app');

ts/windows/calldiagnostic/app.dom.tsx

@@ -7,12 +7,15 @@ import '../sandboxedInit.dom.ts';
 import { CallDiagnosticWindow } from '../../components/CallDiagnosticWindow.dom.tsx';
 import { strictAssert } from '../../util/assert.std.ts';
 import { AppProvider } from '../AppProvider.dom.tsx';
+import { setDocumentLocale } from '../../util/setDocumentLocale.dom.ts';
 
 const { CallDiagnosticWindowProps } = window.Signal;
 strictAssert(CallDiagnosticWindowProps, 'window values not provided');
 const { subscribe, getSnapshot } = CallDiagnosticWindowProps;
 const { i18n } = window.SignalContext;
 
+setDocumentLocale(document);
+
 function App(): JSX.Element | null {
   const diagnosticData = useSyncExternalStore(subscribe, getSnapshot);
 

ts/windows/debuglog/app.dom.tsx

@@ -6,10 +6,13 @@ import '../sandboxedInit.dom.ts';
 import { DebugLogWindow } from '../../components/DebugLogWindow.dom.tsx';
 import { strictAssert } from '../../util/assert.std.ts';
 import { AppProvider } from '../AppProvider.dom.tsx';
+import { setDocumentLocale } from '../../util/setDocumentLocale.dom.ts';
 
 const { DebugLogWindowProps } = window.Signal;
 const { i18n } = window.SignalContext;
 
+setDocumentLocale(document);
+
 strictAssert(DebugLogWindowProps, 'window values not provided');
 
 const app = document.getElementById('app');

ts/windows/permissions/app.dom.tsx

@@ -5,10 +5,13 @@ import '../sandboxedInit.dom.ts';
 import { PermissionsPopup } from '../../components/PermissionsPopup.dom.tsx';
 import { strictAssert } from '../../util/assert.std.ts';
 import { AppProvider } from '../AppProvider.dom.tsx';
+import { setDocumentLocale } from '../../util/setDocumentLocale.dom.ts';
 
 const { PermissionsWindowProps } = window.Signal;
 const { i18n } = window.SignalContext;
 
+setDocumentLocale(document);
+
 strictAssert(PermissionsWindowProps, 'window values not provided');
 
 const { forCalling, forCamera } = PermissionsWindowProps;

ts/windows/screenShare/app.dom.tsx

@@ -7,10 +7,13 @@ import { strictAssert } from '../../util/assert.std.ts';
 import { drop } from '../../util/drop.std.ts';
 import { parseEnvironment, setEnvironment } from '../../environment.std.ts';
 import { AppProvider } from '../AppProvider.dom.tsx';
+import { setDocumentLocale } from '../../util/setDocumentLocale.dom.ts';
 
 const { ScreenShareWindowProps } = window.Signal;
 const { i18n } = window.SignalContext;
 
+setDocumentLocale(document);
+
 strictAssert(ScreenShareWindowProps, 'window values not provided');
 
 setEnvironment(