feat(folio-core): scope Repository and SqlLedgerStore as @SingleIn(AppScope)

Both are app-wide singletons so the SqlDelight-backed flows remain
shared across the graph.

examples/folio/core/src/commonMain/kotlin/app/folio/core/data/Repository.kt

@@ -1,9 +1,12 @@
 package app.folio.core.data
 
 import app.folio.core.platform.Platform
+import dev.zacsweers.metro.AppScope
 import dev.zacsweers.metro.Inject
+import dev.zacsweers.metro.SingleIn
 import kotlinx.coroutines.flow.StateFlow
 
+@SingleIn(AppScope::class)
 @Inject
 class Repository(private val store: LedgerStore) {
     val accounts: StateFlow<List<Account>> = store.accounts

examples/folio/core/src/commonMain/kotlin/app/folio/core/data/SqlLedgerStore.kt

@@ -5,7 +5,9 @@ import app.cash.sqldelight.coroutines.asFlow
 import app.cash.sqldelight.coroutines.mapToList
 import app.cash.sqldelight.coroutines.mapToOneOrNull
 import app.folio.db.LedgerDatabase
+import dev.zacsweers.metro.AppScope
 import dev.zacsweers.metro.Inject
+import dev.zacsweers.metro.SingleIn
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.SupervisorJob
@@ -14,6 +16,7 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
 
+@SingleIn(AppScope::class)
 @Inject
 class SqlLedgerStore(db: LedgerDatabase) : LedgerStore {
     private val queries = db.ledgerQueries