feat(yandex-disk): REST client, repository, and app-folder storages

Add Yandex Disk API (Retrofit + OkHttp), per-vault repository with DB-backed
OAuth token, YandexStorage/YandexStorageAccessor under app:/<uuid>, and a
real YandexVault bootstrap (disk quota, list storages, create/remove).

Expose vault and storage availability: vault is reachable after diskInfo;
each storage combines vault reachability with local init readiness. Map
401 to YandexDiskAuthException and mark the vault unavailable.

Add YandexAccountDao.getByVaultUuid for fresh tokens on each request.

Co-authored-by: Cursor <cursoragent@cursor.com>

data/build.gradle.kts

@@ -48,6 +48,8 @@ dependencies {
     implementation(libs.retrofit.converter.scalars)
     implementation(libs.retrofit.converter.jackson)
 
+    implementation("com.squareup.okhttp3:okhttp:4.12.0")
+
     implementation(libs.androidx.core.ktx)
     testImplementation(libs.junit)
     androidTestImplementation(libs.androidx.junit)