docs: translate all code comments to English (language policy)

Translate every Italian /// XML doc comment, <!-- --> XAML comment, and
// inline comment to English across all source files (Core, App, tests).
Add the language policy to CLAUDE.md (conversation Italian; all code
and docs English). Update one test assertion that checked an Italian
exception message that was also translated.

src/App/ViewModels/TransactionDetailsViewModel.cs

@@ -7,13 +7,13 @@ using PalladiumWallet.Core.Wallet;
 
 namespace PalladiumWallet.App.ViewModels;
 
-/// <summary>Riga input/output per le tabelle della finestra di dettaglio.</summary>
+/// <summary>Input/output row for the transaction detail tables.</summary>
 public sealed record TxIoRow(string Position, string Address, string Amount, bool IsMine);
 
 /// <summary>
-/// ViewModel della finestra di dettaglio transazione: prende un
-/// <see cref="TransactionDetails"/> (assemblato dal server) e ne ricava tutte
-/// le stringhe già formattate e localizzate per la vista. È di sola lettura.
+/// ViewModel for the transaction detail view: takes a
+/// <see cref="TransactionDetails"/> (assembled from server data) and produces
+/// all strings already formatted and localised for the view. Read-only.
 /// </summary>
 public sealed class TransactionDetailsViewModel
 {
@@ -35,14 +35,14 @@ public sealed class TransactionDetailsViewModel
 
         var counterparties = d.CounterpartyAddresses;
         CounterpartyHeader = d.IsIncoming ? loc["tx.from"] : loc["tx.to"];
-        // Una coinbase non ha mittente: le monete sono generate dal mining.
+        // Coinbase has no sender: coins are newly generated by mining.
         CounterpartyText = d.IsCoinbase
             ? loc["tx.coinbase.newcoins"]
             : counterparties.Count > 0
                 ? string.Join(Environment.NewLine, counterparties)
                 : "—";
 
-        // Debito (uscita verso terzi) o Credito (entrata netta sui nostri output).
+        // Debit (outflow to third parties) or Credit (net inflow on our outputs).
         AmountHeader = d.IsIncoming ? loc["tx.credit"] : loc["tx.debit"];
         AmountText = d.IsIncoming
             ? Signed(d.ReceivedSats)