feat: Bitcoin key derivation, secrets storage, and chain-family plumbing

Derives a BIP84 (native SegWit) keypair alongside the existing substrate/
ethereum/tron ones, stores it in MetaAccountSecrets/CloudBackup, persists
bitcoinPublicKey/bitcoinAddress on meta_accounts (DB migration 74->75), and
threads isBitcoinBased through Chain/ChainLocal/mappers/ChainExt/ChainRegistry
the same way isTronBased was wired. Adds BitcoinAddressBackfillMigration,
mirroring TronAddressBackfillMigration, so existing wallets get a Bitcoin
address without re-import.

core-db/src/androidTest/java/io/novafoundation/nova/core_db/dao/Helpers.kt

@@ -58,6 +58,7 @@ fun chainOf(
     isTestNet = false,
     isEthereumBased = false,
     isTronBased = false,
+    isBitcoinBased = false,
     hasCrowdloans = false,
     additional = "",
     governance = "governance",

core-db/src/main/java/io/novafoundation/nova/core_db/AppDatabase.kt

@@ -94,6 +94,7 @@ import io.novafoundation.nova.core_db.migrations.AddStakingTypeToTotalRewards_44
 import io.novafoundation.nova.core_db.migrations.AddSwapOption_48_49
 import io.novafoundation.nova.core_db.migrations.AddTransactionVersionToRuntime_50_51
 import io.novafoundation.nova.core_db.migrations.AddTransferApisTable_29_30
+import io.novafoundation.nova.core_db.migrations.AddBitcoinSupport_74_75
 import io.novafoundation.nova.core_db.migrations.AddTronSupport_73_74
 import io.novafoundation.nova.core_db.migrations.AddTypeExtrasToMetaAccount_68_69
 import io.novafoundation.nova.core_db.migrations.AddVersioningToGovernanceDapps_32_33
@@ -167,7 +168,7 @@ import io.novafoundation.nova.core_db.model.operation.SwapTypeLocal
 import io.novafoundation.nova.core_db.model.operation.TransferTypeLocal
 
 @Database(
-    version = 74,
+    version = 75,
     entities = [
         AccountLocal::class,
         NodeLocal::class,
@@ -273,6 +274,7 @@ abstract class AppDatabase : RoomDatabase() {
                     .addMigrations(AddTypeExtrasToMetaAccount_68_69, AddMultisigCalls_69_70, AddMultisigSupportFlag_70_71)
                     .addMigrations(AddGifts_71_72, AddFieldsToContributions)
                     .addMigrations(AddTronSupport_73_74)
+                    .addMigrations(AddBitcoinSupport_74_75)
                     .build()
             }
             return instance!!

core-db/src/main/java/io/novafoundation/nova/core_db/migrations/74_75_AddBitcoinSupport.kt

@@ -0,0 +1,14 @@
+package io.novafoundation.nova.core_db.migrations
+
+import androidx.room.migration.Migration
+import androidx.sqlite.db.SupportSQLiteDatabase
+
+val AddBitcoinSupport_74_75 = object : Migration(74, 75) {
+
+    override fun migrate(db: SupportSQLiteDatabase) {
+        db.execSQL("ALTER TABLE chains ADD COLUMN isBitcoinBased INTEGER NOT NULL DEFAULT 0")
+
+        db.execSQL("ALTER TABLE meta_accounts ADD COLUMN bitcoinPublicKey BLOB")
+        db.execSQL("ALTER TABLE meta_accounts ADD COLUMN bitcoinAddress BLOB")
+    }
+}

core-db/src/main/java/io/novafoundation/nova/core_db/model/chain/ChainLocal.kt

@@ -23,6 +23,8 @@ data class ChainLocal(
     val isEthereumBased: Boolean,
     @ColumnInfo(defaultValue = "0")
     val isTronBased: Boolean,
+    @ColumnInfo(defaultValue = "0")
+    val isBitcoinBased: Boolean,
     val isTestNet: Boolean,
     @ColumnInfo(defaultValue = "1")
     val hasSubstrateRuntime: Boolean,

core-db/src/main/java/io/novafoundation/nova/core_db/model/chain/account/MetaAccountLocal.kt

@@ -39,6 +39,8 @@ class MetaAccountLocal(
     val typeExtras: SerializedJson?,
     val tronPublicKey: ByteArray? = null,
     val tronAddress: ByteArray? = null,
+    val bitcoinPublicKey: ByteArray? = null,
+    val bitcoinAddress: ByteArray? = null,
 ) {
 
     enum class Status {
@@ -59,6 +61,9 @@ class MetaAccountLocal(
             const val TRON_PUBKEY = "tronPublicKey"
             const val TRON_ADDRESS = "tronAddress"
 
+            const val BITCOIN_PUBKEY = "bitcoinPublicKey"
+            const val BITCOIN_ADDRESS = "bitcoinAddress"
+
             const val NAME = "name"
             const val IS_SELECTED = "isSelected"
             const val POSITION = "position"
@@ -90,7 +95,37 @@ class MetaAccountLocal(
             globallyUniqueId = globallyUniqueId,
             typeExtras = typeExtras,
             tronPublicKey = tronPublicKey,
-            tronAddress = tronAddress
+            tronAddress = tronAddress,
+            bitcoinPublicKey = bitcoinPublicKey,
+            bitcoinAddress = bitcoinAddress,
+        ).also {
+            it.id = id
+        }
+    }
+
+    // We do not use copy as we need explicitly set id
+    fun addBitcoinAccount(
+        bitcoinPublicKey: ByteArray,
+        bitcoinAddress: ByteArray,
+    ): MetaAccountLocal {
+        return MetaAccountLocal(
+            substratePublicKey = substratePublicKey,
+            substrateCryptoType = substrateCryptoType,
+            substrateAccountId = substrateAccountId,
+            ethereumPublicKey = ethereumPublicKey,
+            ethereumAddress = ethereumAddress,
+            name = name,
+            parentMetaId = parentMetaId,
+            isSelected = isSelected,
+            position = position,
+            type = type,
+            status = status,
+            globallyUniqueId = globallyUniqueId,
+            typeExtras = typeExtras,
+            tronPublicKey = tronPublicKey,
+            tronAddress = tronAddress,
+            bitcoinPublicKey = bitcoinPublicKey,
+            bitcoinAddress = bitcoinAddress,
         ).also {
             it.id = id
         }
@@ -109,6 +144,8 @@ class MetaAccountLocal(
         if (!ethereumAddress.contentEquals(other.ethereumAddress)) return false
         if (!tronPublicKey.contentEquals(other.tronPublicKey)) return false
         if (!tronAddress.contentEquals(other.tronAddress)) return false
+        if (!bitcoinPublicKey.contentEquals(other.bitcoinPublicKey)) return false
+        if (!bitcoinAddress.contentEquals(other.bitcoinAddress)) return false
         if (name != other.name) return false
         if (parentMetaId != other.parentMetaId) return false
         if (isSelected != other.isSelected) return false
@@ -130,6 +167,8 @@ class MetaAccountLocal(
         result = 31 * result + (ethereumAddress?.contentHashCode() ?: 0)
         result = 31 * result + (tronPublicKey?.contentHashCode() ?: 0)
         result = 31 * result + (tronAddress?.contentHashCode() ?: 0)
+        result = 31 * result + (bitcoinPublicKey?.contentHashCode() ?: 0)
+        result = 31 * result + (bitcoinAddress?.contentHashCode() ?: 0)
         result = 31 * result + name.hashCode()
         result = 31 * result + (parentMetaId?.hashCode() ?: 0)
         result = 31 * result + isSelected.hashCode()