feat: persist notes on realtime note unload and on interval

The realtime note map has been moved into its own class
to separate the realtime note business logic from the storing logic.

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

src/frontend-config/frontend-config.service.spec.ts

@@ -168,6 +168,7 @@ describe('FrontendConfigService', () => {
           rendererOrigin: domain,
           port: 3000,
           loglevel: Loglevel.ERROR,
+          persistInterval: 10,
         };
         const authConfig: AuthConfig = {
           ...emptyAuthConfig,
@@ -322,6 +323,7 @@ describe('FrontendConfigService', () => {
                   rendererOrigin: renderOrigin ?? domain,
                   port: 3000,
                   loglevel: Loglevel.ERROR,
+                  persistInterval: 10,
                 };
                 const authConfig: AuthConfig = {
                   ...emptyAuthConfig,