fix(invoices): send invoice amounts as exact cent-rounded decimals

Stornorechnung saves still failed: the VAT amount was formatted invariantly
("-615.3757999999999") and re-parsed under the server's de-DE culture as
-6153757999999999, overflowing numeric(10,3) in fds__setInvoice.

- FdsInvoiceData.BuildInvoiceParams: amount params are decimal(10,x) via
  AmountParam/ParseAmount (culture-independent, rounded to cents); amounts
  beyond +/-9,999,999.99 throw InvoiceAmountOutOfRangeException.
- InvoiceService.RegisterInvoiceAsync: refuses such an invoice with a logged
  error (EventId InvoiceAmountRejected) instead of storing a wrong amount.
- Invoice editor: vat_val is cent-rounded decimal, no float noise.
- Tests: InvoiceAmountParamTests replaces the float-based Storno test.
- Bump Azure.Storage.Blobs 12.30.0; OCORE/OCORE_web submodules (AngleSharp
  1.8.3, Azure.Storage.Files.Shares 12.28.0).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Fuchs/Controllers/IntranetController.Invoices2.cs

@@ -475,7 +475,9 @@ public partial class IntranetController
                     {
                         ["Id"]         = d["Id"],
                         ["net_val"]    = net,
-                        ["vat_val"]    = net * vat * 0.01,
+                        // Cent-rounded in decimal like InvoiceDraftCalculator; the former double product
+                        // (e.g. -615.3757999999999) carried float noise into the draft's VAT sums.
+                        ["vat_val"]    = Math.Round((decimal)net * (decimal)vat / 100m, 2, MidpointRounding.AwayFromZero),
                         ["vat"]        = vat == 0 ? "" : vat.ToString("0.00", FuchsPdf.DeCulture) + "%",
                         ["svcnet_val"] = d.no("value_service", 0),
                         ["net"]        = d.no("value", 0),