refactor: clear three small jvmAndroid dependencies of Account's group

- DefaultSignerPermissions moves from model/AccountSettings.kt to
  ExternalSignerButton, its only user. It is the NIP-55 permission request
  sent to an Android signer app at login, built from quartz androidMain types
  (CommandType, Permission); AccountSettings never read it.
- GeohashIdentitySecrets, a plain data class, moves out of the jvmAndroid
  AccountSecrets.kt (which is jvmAndroid for its DataStore keys and legacy
  readers) into its own commonMain file, same package.
- OnchainWalletState moves from commons jvmAndroid to commonMain. It only
  needed kotlinx.coroutines.IO and kotlin.concurrent.Volatile imports; every
  quartz type it uses is already commonMain.

No behaviour change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S7FuNBSKiyVecARSoE4B9P

amethyst/src/main/java/com/vitorpamplona/amethyst/model/AccountSettings.kt

@@ -62,9 +62,7 @@ import com.vitorpamplona.quartz.nip02FollowList.ContactListEvent
 import com.vitorpamplona.quartz.nip17Dm.base.ChatroomKey
 import com.vitorpamplona.quartz.nip17Dm.settings.DmRelayListEvent
 import com.vitorpamplona.quartz.nip28PublicChat.list.PublicChatListEvent
-import com.vitorpamplona.quartz.nip37Drafts.DraftWrapEvent
 import com.vitorpamplona.quartz.nip37Drafts.privateOutbox.PrivateOutboxRelayListEvent
-import com.vitorpamplona.quartz.nip42RelayAuth.RelayAuthEvent
 import com.vitorpamplona.quartz.nip47WalletConnect.Nip47WalletConnect
 import com.vitorpamplona.quartz.nip50Search.SearchRelayListEvent
 import com.vitorpamplona.quartz.nip51Lists.favoriteAlgoFeedsList.FavoriteAlgoFeedsListEvent
@@ -76,8 +74,6 @@ import com.vitorpamplona.quartz.nip51Lists.relayLists.FavoriteRelayListEvent
 import com.vitorpamplona.quartz.nip51Lists.relayLists.IndexerRelayListEvent
 import com.vitorpamplona.quartz.nip51Lists.relayLists.TrustedRelayListEvent
 import com.vitorpamplona.quartz.nip51Lists.simpleGroupList.SimpleGroupListEvent
-import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
-import com.vitorpamplona.quartz.nip55AndroidSigner.api.permission.Permission
 import com.vitorpamplona.quartz.nip57Zaps.ZapReceiptEvent
 import com.vitorpamplona.quartz.nip60Cashu.wallet.CashuWalletEvent
 import com.vitorpamplona.quartz.nip61Nutzaps.info.NutzapInfoEvent
@@ -97,17 +93,6 @@ import kotlinx.serialization.Serializable
 import kotlin.uuid.ExperimentalUuidApi
 import kotlin.uuid.Uuid
 
-val DefaultSignerPermissions =
-    listOf(
-        Permission(CommandType.SIGN_EVENT, RelayAuthEvent.KIND),
-        Permission(CommandType.SIGN_EVENT, DraftWrapEvent.KIND),
-        Permission(CommandType.NIP04_ENCRYPT),
-        Permission(CommandType.NIP04_DECRYPT),
-        Permission(CommandType.NIP44_DECRYPT),
-        Permission(CommandType.NIP44_DECRYPT),
-        Permission(CommandType.DECRYPT_ZAP_EVENT),
-    )
-
 @Stable
 class AccountSettings(
     val keyPair: KeyPair,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedOff/login/ExternalSignerButton.kt

@@ -64,9 +64,12 @@ import com.vitorpamplona.amethyst.commons.ui.stringRes
 import com.vitorpamplona.amethyst.commons.ui.theme.Size0dp
 import com.vitorpamplona.amethyst.commons.ui.theme.Size20dp
 import com.vitorpamplona.amethyst.commons.ui.theme.Size40dp
-import com.vitorpamplona.amethyst.model.DefaultSignerPermissions
+import com.vitorpamplona.quartz.nip37Drafts.DraftWrapEvent
+import com.vitorpamplona.quartz.nip42RelayAuth.RelayAuthEvent
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.CommandType
 import com.vitorpamplona.quartz.nip55AndroidSigner.api.PubKeyResult
 import com.vitorpamplona.quartz.nip55AndroidSigner.api.SignerResult
+import com.vitorpamplona.quartz.nip55AndroidSigner.api.permission.Permission
 import com.vitorpamplona.quartz.nip55AndroidSigner.client.ExternalSignerLogin
 import com.vitorpamplona.quartz.nip55AndroidSigner.client.getExternalSignersInstalled
 import com.vitorpamplona.quartz.utils.Log
@@ -196,3 +199,15 @@ fun ExternalSignerButton(loginViewModel: LoginViewModel) {
         )
     }
 }
+
+/** What Amethyst asks a NIP-55 signer app to pre-approve when the user logs in with it. */
+val DefaultSignerPermissions =
+    listOf(
+        Permission(CommandType.SIGN_EVENT, RelayAuthEvent.KIND),
+        Permission(CommandType.SIGN_EVENT, DraftWrapEvent.KIND),
+        Permission(CommandType.NIP04_ENCRYPT),
+        Permission(CommandType.NIP04_DECRYPT),
+        Permission(CommandType.NIP44_DECRYPT),
+        Permission(CommandType.NIP44_DECRYPT),
+        Permission(CommandType.DECRYPT_ZAP_EVENT),
+    )

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/nipBCOnchainZaps/OnchainWalletState.kt

@@ -31,12 +31,14 @@ import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.IO
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
+import kotlin.concurrent.Volatile
 
 /**
  * A snapshot of the account's NIP-BC on-chain wallet: what is sitting on the

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/preferences/GeohashIdentitySecrets.kt

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.model.preferences
+
+/**
+ * The account's location-chat identity: the seed its per-geohash throwaway keys
+ * come from, and the handle it posts under.
+ *
+ * # Why this is not two more fields on [AccountSecrets]
+ *
+ * Every account save mirrors a whole [AccountSecrets], built field by field from
+ * `AccountSettings` — which does not hold these, because they are owned by
+ * `GeohashChatIdentityState` rather than by the settings object. Folding them in
+ * would make each save write null over them, and the group save uses
+ * `putOrRemove`, so null *deletes*. The seed would vanish on the next unrelated
+ * save and every geohash identity the user has would silently change. A separate
+ * group with its own save path cannot be wiped by a save that does not know
+ * about it.
+ *
+ * # Why encrypted
+ *
+ * The whole point of the seed is that the identities derived from it are
+ * unlinkable to the npub. Anyone who can read it can link every cell the user
+ * has ever posted in, to each other and to the device, which is exactly what the
+ * feature exists to prevent. It was in an encrypted file before; it stays in one.
+ */
+data class GeohashIdentitySecrets(
+    val deviceSeed: String? = null,
+    val nickname: String? = null,
+)

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/model/preferences/AccountSecrets.kt

@@ -152,33 +152,6 @@ fun readLegacyAccountSecrets(source: LegacyPreferenceSource) =
         legacyZapPaymentRequestServer = source.getString(LegacyAccountSecretNames.ZAP_PAYMENT_REQUEST_SERVER),
     )
 
-/**
- * The account's location-chat identity: the seed its per-geohash throwaway keys
- * come from, and the handle it posts under.
- *
- * # Why this is not two more fields on [AccountSecrets]
- *
- * Every account save mirrors a whole [AccountSecrets], built field by field from
- * `AccountSettings` — which does not hold these, because they are owned by
- * `GeohashChatIdentityState` rather than by the settings object. Folding them in
- * would make each save write null over them, and the group save uses
- * `putOrRemove`, so null *deletes*. The seed would vanish on the next unrelated
- * save and every geohash identity the user has would silently change. A separate
- * group with its own save path cannot be wiped by a save that does not know
- * about it.
- *
- * # Why encrypted
- *
- * The whole point of the seed is that the identities derived from it are
- * unlinkable to the npub. Anyone who can read it can link every cell the user
- * has ever posted in, to each other and to the device, which is exactly what the
- * feature exists to prevent. It was in an encrypted file before; it stays in one.
- */
-data class GeohashIdentitySecrets(
-    val deviceSeed: String? = null,
-    val nickname: String? = null,
-)
-
 /** Keys for [GeohashIdentitySecrets] inside an [EncryptedDataStore]. */
 internal object GeohashIdentityKeys {
     val deviceSeed = stringPreferencesKey(LegacyAccountSecretNames.GEOHASH_DEVICE_SEED)