Add idb-keyval backed archival storage (#9754)

* Add idb-keyval backed archival storage

* Cleanup

* Remove test

src/storage/archive/db/index.ts

@@ -0,0 +1,22 @@
+import {MMKV} from '@bsky.app/react-native-mmkv'
+
+import {type DB} from '#/storage/archive/db/types'
+
+export function create({id}: {id: string}): DB {
+  const store = new MMKV({id})
+
+  return {
+    async get(key: string): Promise<string | undefined> {
+      return store.getString(key) ?? undefined
+    },
+    async set(key: string, value: string): Promise<void> {
+      store.set(key, value)
+    },
+    async delete(key: string): Promise<void> {
+      store.delete(key)
+    },
+    async clear(): Promise<void> {
+      store.clearAll()
+    },
+  }
+}

src/storage/archive/db/index.web.ts

@@ -0,0 +1,22 @@
+import {clear, createStore, del, get, set} from 'idb-keyval'
+
+import {type DB} from '#/storage/archive/db/types'
+
+export function create({id}: {id: string}): DB {
+  const store = createStore(id, id)
+
+  return {
+    async get(key: string): Promise<string | undefined> {
+      return get(key, store) ?? undefined
+    },
+    async set(key: string, value: string): Promise<void> {
+      await set(key, value, store)
+    },
+    async delete(key: string): Promise<void> {
+      await del(key, store)
+    },
+    async clear(): Promise<void> {
+      await clear(store)
+    },
+  }
+}

src/storage/archive/db/types.ts

@@ -0,0 +1,6 @@
+export type DB = {
+  get(key: string): Promise<string | undefined>
+  set(key: string, value: string): Promise<void>
+  delete(key: string): Promise<void>
+  clear(): Promise<void>
+}