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.API/Transactions/FireWebhook/Endpoint.cs

@@ -0,0 +1,65 @@
+using Going.Plaid;
+using Going.Plaid.Entity;
+
+namespace FiscalOS.API.Transactions.FireWebhook;
+
+internal static class Endpoint
+{
+  private const string Route = "/fire-webhook";
+
+  public static RouteHandlerBuilder MapFireWebhookEndpoint(this RouteGroupBuilder groupBuilder)
+  {
+    return groupBuilder.MapPost(Route, HandleAsync);
+  }
+
+  private static async Task<IResult> HandleAsync(
+    HttpContext httpContext,
+    [FromBody] Request request,
+    [FromServices] AppDbContext appDbContext,
+    [FromServices] IEncryptor encryptor,
+    [FromServices] PlaidClient plaidClient,
+    CancellationToken ct
+  )
+  {
+    var userId = httpContext.GetUserId();
+
+    var user = await appDbContext.Users
+      .Include(u => u.Accounts.Where(a => a.Id.ToString() == request.AccountId))
+      .ThenInclude(static a => a.Institution!)
+      .ThenInclude(static i => i.Metadata)
+      .FirstOrDefaultAsync(u => u.Id == userId, ct);
+
+    if (user is null)
+    {
+      return Results.Unauthorized();
+    }
+
+    if (user.Accounts.Any() is false)
+    {
+      return Results.NotFound();
+    }
+
+    var plaidMetadata = (PlaidInstitutionMetadata?)user.Accounts.First().Institution?.Metadata;
+
+    if (plaidMetadata is null)
+    {
+      return Results.InternalServerError("No metadata associated with account");
+    }
+
+    var accessToken = await encryptor.DecryptAsyncFor(user, plaidMetadata.EncryptedAccessToken, ct);
+
+    var fireEventResponse = await plaidClient.SandboxItemFireWebhookAsync(new()
+    {
+      AccessToken = accessToken,
+      WebhookType = SandboxItemFireWebhookRequestWebhookTypeEnum.Transactions,
+      WebhookCode = SandboxItemFireWebhookRequestWebhookCodeEnum.SyncUpdatesAvailable,
+    });
+
+    if (fireEventResponse.IsSuccessStatusCode is false)
+    {
+      return Results.InternalServerError(fireEventResponse.Error?.ErrorMessage);
+    }
+
+    return Results.Ok(new { fireEventResponse.RequestId, fireEventResponse.WebhookFired });
+  }
+}