Add native Solana support: address derivation, accounts, signing, backfill migration, CloudBackup wiring

Same read/send-capable chain-family pattern as Tron/Bitcoin, but for
Ed25519/SLIP-0010 instead of secp256k1/BIP32 (Solana's account id IS its
raw public key, so no separate address-hash derivation step is needed).

- SLIP-0010 Ed25519 keypair derivation (Bip32Ed25519KeypairFactory),
  cross-validated against an independent slip10 reference implementation
  and pinned to a known-good test vector.
- Chain.isSolanaBased / Chain.Asset.Type.SolanaNative wired through every
  chain-mapper, account-model, and signer dispatch site (mirrors the
  existing Tron/Bitcoin wiring exactly).
- SolanaAddressBackfillMigration derives Solana keys for wallets created
  before this support existed, same self-healing no-stuck-flag design as
  the Tron/Bitcoin backfills - also fixed a latent bug in those two
  migrations where MetaAccountSecrets/MetaAccountLocal.addXAccount()
  dropped sibling chain-family fields on a re-run.
- Room migration 75->76 adds isSolanaBased/solanaPublicKey/solanaAddress
  columns.
- CloudBackup's already-reserved solanaAddress/SolanaSecrets fields are
  now actually read/written by RealLocalAccountsCloudBackupFacade; also
  fixed isCompletelyEmpty() to check solana, so a Solana-only wallet
  doesn't get silently dropped from backup.

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

@@ -59,6 +59,7 @@ fun chainOf(
     isEthereumBased = false,
     isTronBased = false,
     isBitcoinBased = false,
+    isSolanaBased = false,
     hasCrowdloans = false,
     additional = "",
     governance = "governance",

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

@@ -95,6 +95,7 @@ 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.AddSolanaSupport_75_76
 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
@@ -168,7 +169,7 @@ import io.novafoundation.nova.core_db.model.operation.SwapTypeLocal
 import io.novafoundation.nova.core_db.model.operation.TransferTypeLocal
 
 @Database(
-    version = 75,
+    version = 76,
     entities = [
         AccountLocal::class,
         NodeLocal::class,
@@ -275,6 +276,7 @@ abstract class AppDatabase : RoomDatabase() {
                     .addMigrations(AddGifts_71_72, AddFieldsToContributions)
                     .addMigrations(AddTronSupport_73_74)
                     .addMigrations(AddBitcoinSupport_74_75)
+                    .addMigrations(AddSolanaSupport_75_76)
                     .build()
             }
             return instance!!

core-db/src/main/java/io/novafoundation/nova/core_db/migrations/75_76_AddSolanaSupport.kt

@@ -0,0 +1,14 @@
+package io.novafoundation.nova.core_db.migrations
+
+import androidx.room.migration.Migration
+import androidx.sqlite.db.SupportSQLiteDatabase
+
+val AddSolanaSupport_75_76 = object : Migration(75, 76) {
+
+    override fun migrate(db: SupportSQLiteDatabase) {
+        db.execSQL("ALTER TABLE chains ADD COLUMN isSolanaBased INTEGER NOT NULL DEFAULT 0")
+
+        db.execSQL("ALTER TABLE meta_accounts ADD COLUMN solanaPublicKey BLOB")
+        db.execSQL("ALTER TABLE meta_accounts ADD COLUMN solanaAddress BLOB")
+    }
+}

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

@@ -25,6 +25,8 @@ data class ChainLocal(
     val isTronBased: Boolean,
     @ColumnInfo(defaultValue = "0")
     val isBitcoinBased: Boolean,
+    @ColumnInfo(defaultValue = "0")
+    val isSolanaBased: 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

@@ -41,6 +41,8 @@ class MetaAccountLocal(
     val tronAddress: ByteArray? = null,
     val bitcoinPublicKey: ByteArray? = null,
     val bitcoinAddress: ByteArray? = null,
+    val solanaPublicKey: ByteArray? = null,
+    val solanaAddress: ByteArray? = null,
 ) {
 
     enum class Status {
@@ -64,6 +66,9 @@ class MetaAccountLocal(
             const val BITCOIN_PUBKEY = "bitcoinPublicKey"
             const val BITCOIN_ADDRESS = "bitcoinAddress"
 
+            const val SOLANA_PUBKEY = "solanaPublicKey"
+            const val SOLANA_ADDRESS = "solanaAddress"
+
             const val NAME = "name"
             const val IS_SELECTED = "isSelected"
             const val POSITION = "position"
@@ -98,6 +103,8 @@ class MetaAccountLocal(
             tronAddress = tronAddress,
             bitcoinPublicKey = bitcoinPublicKey,
             bitcoinAddress = bitcoinAddress,
+            solanaPublicKey = solanaPublicKey,
+            solanaAddress = solanaAddress,
         ).also {
             it.id = id
         }
@@ -126,6 +133,8 @@ class MetaAccountLocal(
             tronAddress = tronAddress,
             bitcoinPublicKey = bitcoinPublicKey,
             bitcoinAddress = bitcoinAddress,
+            solanaPublicKey = solanaPublicKey,
+            solanaAddress = solanaAddress,
         ).also {
             it.id = id
         }
@@ -151,7 +160,46 @@ class MetaAccountLocal(
             globallyUniqueId = globallyUniqueId,
             typeExtras = typeExtras,
             tronPublicKey = tronPublicKey,
-            tronAddress = tronAddress
+            tronAddress = tronAddress,
+            // Previously missing - dropped bitcoin/solana on any account already carrying them. Since
+            // this migration is deliberately unconditional/self-healing (re-runs every app start to
+            // recover from a since-fixed bug re-losing a keypair), a re-run after Bitcoin/Solana were
+            // already backfilled would silently wipe them back to null. See addBitcoinAccount/
+            // addSolanaAccount - every addXAccount must carry every sibling chain-family field forward.
+            bitcoinPublicKey = bitcoinPublicKey,
+            bitcoinAddress = bitcoinAddress,
+            solanaPublicKey = solanaPublicKey,
+            solanaAddress = solanaAddress,
+        ).also {
+            it.id = id
+        }
+    }
+
+    // We do not use copy as we need explicitly set id
+    fun addSolanaAccount(
+        solanaPublicKey: ByteArray,
+        solanaAddress: 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,
+            solanaPublicKey = solanaPublicKey,
+            solanaAddress = solanaAddress,
         ).also {
             it.id = id
         }
@@ -172,6 +220,8 @@ class MetaAccountLocal(
         if (!tronAddress.contentEquals(other.tronAddress)) return false
         if (!bitcoinPublicKey.contentEquals(other.bitcoinPublicKey)) return false
         if (!bitcoinAddress.contentEquals(other.bitcoinAddress)) return false
+        if (!solanaPublicKey.contentEquals(other.solanaPublicKey)) return false
+        if (!solanaAddress.contentEquals(other.solanaAddress)) return false
         if (name != other.name) return false
         if (parentMetaId != other.parentMetaId) return false
         if (isSelected != other.isSelected) return false
@@ -195,6 +245,8 @@ class MetaAccountLocal(
         result = 31 * result + (tronAddress?.contentHashCode() ?: 0)
         result = 31 * result + (bitcoinPublicKey?.contentHashCode() ?: 0)
         result = 31 * result + (bitcoinAddress?.contentHashCode() ?: 0)
+        result = 31 * result + (solanaPublicKey?.contentHashCode() ?: 0)
+        result = 31 * result + (solanaAddress?.contentHashCode() ?: 0)
         result = 31 * result + name.hashCode()
         result = 31 * result + (parentMetaId?.hashCode() ?: 0)
         result = 31 * result + isSelected.hashCode()