Adds a WalletDocument.WatchAddresses field and WalletLoader.NewFromAddresses
to build an ImportedKeyAccount with no private key at all (unlike xpub/WIF
imports, which can still derive/hold key material). ScriptKind is inferred
from the address itself via a new DerivationPaths.KindFor helper. Signing
already refuses to run for any IsWatchOnly account (TransactionFactory), so
this only had to wire up construction/reload of the new account shape.
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.
davide