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.

runtime/src/main/java/io/novafoundation/nova/runtime/ext/ChainExt.kt

@@ -272,6 +272,7 @@ fun Chain.requireGenesisHash() = requireNotNull(genesisHash)
 fun Chain.addressOf(accountId: ByteArray): String {
     return when {
         isTronBased -> accountId.toTronAddress()
+        isBitcoinBased -> accountId.toBitcoinAddress()
         isEthereumBased -> accountId.toEthereumAddress()
         else -> accountId.toAddress(addressPrefix.toShort())
     }
@@ -282,7 +283,7 @@ fun Chain.addressOf(accountId: AccountIdKey): String {
 }
 
 fun Chain.legacyAddressOfOrNull(accountId: ByteArray): String? {
-    return if (isEthereumBased || isTronBased) {
+    return if (isEthereumBased || isTronBased || isBitcoinBased) {
         null
     } else {
         legacyAddressPrefix?.let { accountId.toAddress(it.toShort()) }
@@ -296,6 +297,7 @@ fun ByteArray.toEthereumAddress(): String {
 fun Chain.accountIdOf(address: String): ByteArray {
     return when {
         isTronBased -> address.tronAddressToAccountId()
+        isBitcoinBased -> address.bitcoinAddressToAccountId()
         isEthereumBased -> address.asEthereumAddress().toAccountId().value
         else -> address.toAccountId()
     }
@@ -329,6 +331,7 @@ fun Chain.accountIdOrNull(address: String): ByteArray? {
 
 fun Chain.emptyAccountId() = when {
     isTronBased -> emptyTronAccountId()
+    isBitcoinBased -> emptyBitcoinAccountId()
     isEthereumBased -> emptyEthereumAccountId()
     else -> emptySubstrateAccountId()
 }
@@ -342,6 +345,7 @@ fun Chain.accountIdOrDefault(maybeAddress: String): ByteArray {
 fun Chain.accountIdOf(publicKey: ByteArray): ByteArray {
     return when {
         isTronBased -> publicKey.tronPublicKeyToAccountId()
+        isBitcoinBased -> publicKey.bitcoinPublicKeyToAccountId()
         isEthereumBased -> publicKey.asEthereumPublicKey().toAccountId().value
         else -> publicKey.substrateAccountId()
     }
@@ -361,13 +365,15 @@ fun Chain.multiAddressOf(accountId: ByteArray): MultiAddress {
 
 fun Chain.isValidAddress(address: String): Boolean {
     return runCatching {
-        if (isEthereumBased) {
-            address.asEthereumAddress().isValid()
-        } else {
-            address.toAccountId() // verify supplied address can be converted to account id
+        when {
+            isBitcoinBased -> address.isValidBitcoinAddress()
+            isEthereumBased -> address.asEthereumAddress().isValid()
+            else -> {
+                address.toAccountId() // verify supplied address can be converted to account id
 
-            addressPrefix.toShort() == address.addressPrefix() ||
-                legacyAddressPrefix?.toShort() == address.addressPrefix()
+                addressPrefix.toShort() == address.addressPrefix() ||
+                    legacyAddressPrefix?.toShort() == address.addressPrefix()
+            }
         }
     }.getOrDefault(false)
 }

runtime/src/main/java/io/novafoundation/nova/runtime/multiNetwork/ChainRegistry.kt

@@ -221,11 +221,11 @@ class ChainRegistry(
     }
 
     private suspend fun registerConnection(chain: Chain): ChainConnection? {
-        // Tron nodes are plain REST APIs (TronGrid), not WSS JSON-RPC endpoints - ChainConnection's
-        // SocketService can only speak the latter, so attempting to set one up here would hang
-        // indefinitely instead of failing fast. Tron balance/transfer operations already go through
-        // their own dedicated TronGridApi client, independent of this connection pool.
-        if (chain.isTronBased) return null
+        // Tron/Bitcoin nodes are plain REST APIs (TronGrid / mempool.space), not WSS JSON-RPC endpoints -
+        // ChainConnection's SocketService can only speak the latter, so attempting to set one up here would
+        // hang indefinitely instead of failing fast. Balance/transfer operations for both go through their
+        // own dedicated REST API clients, independent of this connection pool.
+        if (chain.isTronBased || chain.isBitcoinBased) return null
 
         val connection = connectionPool.setupConnection(chain)
 

runtime/src/main/java/io/novafoundation/nova/runtime/multiNetwork/chain/mappers/DomainToLocalChainMapper.kt

@@ -128,6 +128,7 @@ fun mapChainToLocal(chain: Chain, gson: Gson): ChainLocal {
         legacyPrefix = chain.legacyAddressPrefix,
         isEthereumBased = chain.isEthereumBased,
         isTronBased = chain.isTronBased,
+        isBitcoinBased = chain.isBitcoinBased,
         isTestNet = chain.isTestNet,
         hasSubstrateRuntime = chain.hasSubstrateRuntime,
         pushSupport = chain.pushSupport,

runtime/src/main/java/io/novafoundation/nova/runtime/multiNetwork/chain/mappers/LocalToDomainChainMapper.kt

@@ -276,6 +276,7 @@ fun mapChainLocalToChain(
             legacyAddressPrefix = legacyPrefix,
             isEthereumBased = isEthereumBased,
             isTronBased = isTronBased,
+            isBitcoinBased = isBitcoinBased,
             isTestNet = isTestNet,
             hasCrowdloans = hasCrowdloans,
             pushSupport = pushSupport,

runtime/src/main/java/io/novafoundation/nova/runtime/multiNetwork/chain/mappers/RemoteToLocalChainMappers.kt

@@ -21,6 +21,7 @@ import io.novafoundation.nova.runtime.multiNetwork.chain.remote.model.ChainRemot
 
 private const val ETHEREUM_OPTION = "ethereumBased"
 private const val TRON_OPTION = "tronBased"
+private const val BITCOIN_OPTION = "bitcoinBased"
 private const val CROWDLOAN_OPTION = "crowdloans"
 private const val TESTNET_OPTION = "testnet"
 private const val PROXY_OPTION = "proxy"
@@ -92,6 +93,7 @@ fun mapRemoteChainToLocal(
             legacyPrefix = legacyAddressPrefix,
             isEthereumBased = ETHEREUM_OPTION in optionsOrEmpty,
             isTronBased = TRON_OPTION in optionsOrEmpty,
+            isBitcoinBased = BITCOIN_OPTION in optionsOrEmpty,
             isTestNet = TESTNET_OPTION in optionsOrEmpty,
             hasCrowdloans = CROWDLOAN_OPTION in optionsOrEmpty,
             supportProxy = PROXY_OPTION in optionsOrEmpty,

runtime/src/main/java/io/novafoundation/nova/runtime/multiNetwork/chain/model/Chain.kt

@@ -33,6 +33,7 @@ data class Chain(
     val types: Types?,
     val isEthereumBased: Boolean,
     val isTronBased: Boolean,
+    val isBitcoinBased: Boolean,
     val isTestNet: Boolean,
     val source: Source,
     val hasSubstrateRuntime: Boolean,