Feature/protocol handlers

* Added account selection for protocol links when multiple connected accounts are available, including mailto: links
* Added support for handling mailto: links in an already-open PWA/session instead of always opening a new tab
* Added webcal: protocol handling for calendar links
* Added account selection for webcal: links when multiple calendar-capable accounts are connected
* Added an import-or-subscribe choice for detected webcal calendars
* Added protocol handler settings for registering mail and calendar handlers and choosing the open mode
* Added service worker/session coordination for passing protocol requests between browser/PWA contexts
* Added tests and translations for the new protocol handler flows

app/[locale]/layout.tsx

@@ -5,6 +5,7 @@ import { CalendarAlertProvider } from "@/components/providers/calendar-alert-pro
 import { EmbeddedBridgeProvider } from "@/components/providers/embedded-bridge-provider";
 import { RateLimitToastProvider } from "@/components/providers/rate-limit-toast-provider";
 import { TourProvider } from "@/components/tour/tour-provider";
+import { ProtocolLaunchHandlerProvider } from "@/components/protocol/protocol-launch-handler-provider";
 import { locales } from "@/i18n/routing";
 
 export default async function LocaleLayout({
@@ -32,7 +33,9 @@ export default async function LocaleLayout({
           <RateLimitToastProvider>
             <EmbeddedBridgeProvider>
               <TourProvider>
-                {children}
+                <ProtocolLaunchHandlerProvider>
+                  {children}
+                </ProtocolLaunchHandlerProvider>
               </TourProvider>
             </EmbeddedBridgeProvider>
           </RateLimitToastProvider>