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.Core/Accounts/Account.cs

@@ -1,3 +1,5 @@
+using FiscalOS.Core.Transactions;
+
 namespace FiscalOS.Core.Accounts;
 
 public sealed class Account : Entity
@@ -11,6 +13,9 @@ public sealed class Account : Entity
   private readonly List<Balance> _balances = [];
   public IEnumerable<Balance> Balances => _balances;
 
+  private readonly List<Transaction> _transactions = [];
+  public IEnumerable<Transaction> Transactions => _transactions;
+
   public static Account From(Guid institutionId, string name, AccountMetadata accountMetadata)
   {
     return new()
@@ -27,4 +32,11 @@ public sealed class Account : Entity
 
     _balances.Add(balance);
   }
+
+  public void AddTransaction(Transaction transaction)
+  {
+    ArgumentNullException.ThrowIfNull(transaction);
+
+    _transactions.Add(transaction);
+  }
 }