feat: add local notifications management and UI integration

src/main/level/sublevels/index.ts

@@ -8,3 +8,4 @@ export * from "./keys";
 export * from "./themes";
 export * from "./download-sources";
 export * from "./downloadSourcesCheckTimestamp";
+export * from "./local-notifications";

src/main/level/sublevels/keys.ts

@@ -20,4 +20,5 @@ export const levelKeys = {
   downloadSources: "downloadSources",
   downloadSourcesCheckBaseline: "downloadSourcesCheckBaseline", // When we last started the app
   downloadSourcesSinceValue: "downloadSourcesSinceValue", // The 'since' value API used (for modal comparison)
+  localNotifications: "localNotifications",
 };

src/main/level/sublevels/local-notifications.ts

@@ -0,0 +1,11 @@
+import type { LocalNotification } from "@types";
+
+import { db } from "../level";
+import { levelKeys } from "./keys";
+
+export const localNotificationsSublevel = db.sublevel<
+  string,
+  LocalNotification
+>(levelKeys.localNotifications, {
+  valueEncoding: "json",
+});