feat: [BBND-1376] Support external wallets in the SDK

[rubenbermejo3]

Description:
This PR implements support for external wallets in the SDK, allowing external systems to construct transactions without executing them, enabling custom signing and submission workflows.

• Add EXTERNAL_HEDERA and EXTERNAL_EVM wallet types to SupportedWallets enum
• Add SerializedTransactionData and TransactionMetadata interfaces for external transaction handling
• Create ExternalHederaTransactionAdapter and ExternalEVMTransactionAdapter for transaction serialization
• Add ExternalWalletSettings interface with validStartOffsetMinutes configuration
• Update TransactionService with isExternalWallet() method and handler registration
• Modify all command responses to include optional serializedTransactionData field
• Update all command handlers to handle external wallet conditional logic
• Add union types to public API methods returning TransactionResult | SerializedTransactionData
• Update ConnectCommandHandler to support external wallet settings configuration
• Register external adapters in dependency injection container
• Export new types and interfaces in public API

Related issue(s):

Fixes #BBND-1376

Notes for reviewer:

• External wallets return serialized transaction bytes instead of executing transactions
• EXTERNAL_HEDERA provides native Hedera transaction bytes
• EXTERNAL_EVM provides EVM-compatible RLP encoded transactions
• All existing functionality remains unchanged for regular wallet types
• Includes proper error handling and validation for external wallet operations

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[swirlds-automation]

✅ Snyk checks have passed. No issues have been found so far.

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[ruben-martinez-iob]

Severidad	Descripción
Baja	Los build* usan throw new Error(...) (plain). El port-in usa exclusivamente errores tipados (BaseError). EmptyResponse (ErrorCode 30008) ya existe para este caso. Ver detalle debajo.

Detalle: reemplazar build* con error no tipado

Archivos afectados (39 ocurrencias totales):

Archivo	Ocurrencias
packages/sdk/src/port/in/StableCoin.ts	22
packages/sdk/src/port/in/Role.ts	10
packages/sdk/src/port/in/CustomFees.ts	3
packages/sdk/src/port/in/Management.ts	3
packages/sdk/src/port/in/ReserveDataFeed.ts	1

Cambio a aplicar en cada archivo:

// 1. Añadir import (relativo desde packages/sdk/src/port/in/)
import { EmptyResponse } from '../../app/service/error/EmptyResponse.js';

// 2. Sustituir todas las guardas (patrón: replace_all)
// Antes
if (!response.serializedTransactionData) throw new Error("Expected serialized transaction data but none was returned");
// Después
if (!response.serializedTransactionData) throw new EmptyResponse('buildXxx');

Referencia: mismo patrón usado en TransactionService.ts:350:

if (!res.id) throw new EmptyResponse(className);

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