feat: add Plaid transaction handling and async queue processing

- introduced new migration to add Cursor column to AccountMetadata.
- updated AppDbContext model snapshot to reflect changes in the database schema.
- implemented async queue processing with ChannelAsyncQueue and AsyncQueueHostedService.
- created Plaid transaction handlers for added, modified, and removed transactions.
- developed PlaidTransactionService and PlaidTransactionSyncer for syncing transactions.
- added SyncUpdatesProcessor to handle sync updates from Plaid.
- updated tests to accommodate changes in institution and account metadata handling.

src/FiscalOS.Infra/Transactions/Plaid/PlaidTransactionService.cs

@@ -0,0 +1,58 @@
+namespace FiscalOS.Infra.Transactions.Plaid;
+
+internal interface IPlaidTransactionService
+{
+  IAsyncEnumerable<TransactionsSyncResponse> SyncTransactionsForAccountAsync(
+    string accessToken,
+    string accountId,
+    string? initialCursor = null
+  );
+}
+
+internal sealed class PlaidTransactionService : IPlaidTransactionService
+{
+  private readonly PlaidClient _client;
+
+  private PlaidTransactionService(PlaidClient client)
+  {
+    _client = client;
+  }
+
+  public static PlaidTransactionService From(IServiceProvider sp)
+  {
+    var client = sp.GetRequiredService<PlaidClient>();
+    return new(client);
+  }
+
+  public async IAsyncEnumerable<TransactionsSyncResponse> SyncTransactionsForAccountAsync(
+    string accessToken,
+    string accountId,
+    string? initialCursor = null
+  )
+  {
+    TransactionsSyncResponse? response;
+    var cursor = initialCursor;
+
+    do
+    {
+      response = await _client.TransactionsSyncAsync(new()
+      {
+        AccessToken = accessToken,
+        Cursor = cursor,
+        Count = 500,
+        Options = new()
+        {
+          AccountId = accountId,
+        }
+      }).ConfigureAwait(false);
+
+      if (response.Error?.ErrorCode is "TRANSACTIONS_SYNC_MUTATION_DURING_PAGINATION")
+      {
+        continue;
+      }
+
+      cursor = response.NextCursor;
+      yield return response;
+    } while (response is not null && response.HasMore);
+  }
+}