Feat: Encrypt and include seed words in account export

Encrypts the seed words using NIP-44 and adds them to the account export data. This ensures that mnemonic phrases are securely backed up along with other account details during the export process.

app/src/main/java/com/greenart7c3/nostrsigner/models/AccountExport.kt

@@ -10,17 +10,19 @@ import com.fasterxml.jackson.module.kotlin.readValue
  */
 @Immutable
 data class AccountExportData(
-    @JsonProperty("npub")
+    @param:JsonProperty("npub")
     val npub: String,
-    @JsonProperty("name")
+    @param:JsonProperty("name")
     val name: String,
-    @JsonProperty("nsec")
+    @param:JsonProperty("nsec")
     val nsec: String?,
-    @JsonProperty("signPolicy")
+    @param:JsonProperty("seedWords")
+    val seedWords: String,
+    @param:JsonProperty("signPolicy")
     val signPolicy: Int,
-    @JsonProperty("picture")
+    @param:JsonProperty("picture")
     val picture: String?,
-    @JsonProperty("didBackup")
+    @param:JsonProperty("didBackup")
     val didBackup: Boolean,
 )
 
@@ -29,13 +31,13 @@ data class AccountExportData(
  */
 @Immutable
 data class BulkAccountExport(
-    @JsonProperty("version")
+    @param:JsonProperty("version")
     val version: String = "1.0",
-    @JsonProperty("exportDate")
+    @param:JsonProperty("exportDate")
     val exportDate: Long = System.currentTimeMillis() / 1000,
-    @JsonProperty("accountCount")
+    @param:JsonProperty("accountCount")
     val accountCount: Int,
-    @JsonProperty("accounts")
+    @param:JsonProperty("accounts")
     val accounts: List<AccountExportData>,
 ) {
     companion object {

app/src/main/java/com/greenart7c3/nostrsigner/service/AccountExportService.kt

@@ -64,6 +64,7 @@ object AccountExportService {
      */
     private fun accountToExportData(account: Account, password: String): AccountExportData {
         val privKey = account.signer.keyPair.privKey
+        val encrypedSeedWords = if (account.seedWords.isNotEmpty()) account.signer.signerSync.nip44Encrypt(account.seedWords.joinToString(" "), account.hexKey) else ""
 
         // Encrypt private key with password (NIP-49) or use nsec if no password
         val encryptedNsec = if (privKey != null) {
@@ -83,6 +84,7 @@ object AccountExportService {
             signPolicy = account.signPolicy,
             picture = account.picture.value,
             didBackup = account.didBackup,
+            seedWords = encrypedSeedWords,
         )
     }
 }