feat: ZSA-aware transaction history (list + detail view)

- Add zsa_value + asset_id columns to transactions table
- Compute ZSA summary in summarize_tx (first asset net amount)
- Add asset_display helper fn (resolved from name or desc_hash, fallback ZEC)
- Tx struct: zsaValue, assetId, assetDisplay fields
- TxNote/TxSpend: idAsset + assetDisplay fields (join assets in queries)
- TransactionTile shows ZSA value below ZEC amount
- Tx detail page shows asset name and raw value for ZSA notes/spends
- Fix calculate_balance to only count ZEC notes (id_asset IS NULL)
- Fix max_spendable to only count ZEC notes

Author: hhanh00

lib/pages/account.dart

@@ -690,6 +690,8 @@ List<Widget> showTxHistory(BuildContext context, List<Tx> transactions) {
           date: tx.time,
           id: tx.id,
           onTap: () => gotoTransaction(context, tx.id),
+          zsaValue: tx.zsaValue != 0 ? BigInt.from(tx.zsaValue) : null,
+          zsaLabel: tx.zsaValue != 0 ? tx.assetDisplay : null,
         );
 
         return Column(children: [

lib/pages/tx_view.dart

@@ -135,9 +135,12 @@ class TxViewPageState extends ConsumerState<TxViewPage> {
       ...txd.spends.expand(
         (n) => [
           ListTile(title: Text("Pool"), subtitle: CopyableText(poolToString(n.pool))),
+          ListTile(title: Text("Asset"), subtitle: CopyableText(n.assetDisplay)),
           ListTile(
             title: Text("Value"),
-            subtitle: zatToText(n.value, selectable: true),
+            subtitle: n.idAsset != null
+                ? Text(n.value.toString())
+                : zatToText(n.value, selectable: true),
           ),
           Divider(),
         ],
@@ -146,9 +149,12 @@ class TxViewPageState extends ConsumerState<TxViewPage> {
       ...txd.notes.expand(
         (n) => [
           ListTile(title: Text("Pool"), subtitle: CopyableText(poolToString(n.pool))),
+          ListTile(title: Text("Asset"), subtitle: CopyableText(n.assetDisplay)),
           ListTile(
             title: Text("Value"),
-            subtitle: zatToText(n.value, selectable: true),
+            subtitle: n.idAsset != null
+                ? Text(n.value.toString())
+                : zatToText(n.value, selectable: true),
           ),
           Divider(),
         ],

lib/src/rust/api/account.dart

@@ -387,6 +387,9 @@ sealed class Tx with _$Tx {
     required PlatformInt64 value,
     int? tpe,
     String? category,
+    required PlatformInt64 zsaValue,
+    int? assetId,
+    required String assetDisplay,
   }) = _Tx;
 }
 
@@ -494,6 +497,7 @@ class TxNote {
   final bool locked;
   final String? memo;
   final int? idAsset;
+  final String assetDisplay;
 
   const TxNote({
     required this.id,
@@ -506,6 +510,7 @@ class TxNote {
     required this.locked,
     this.memo,
     this.idAsset,
+    required this.assetDisplay,
   });
 
   static Future<TxNote> default_() =>
@@ -522,7 +527,8 @@ class TxNote {
       value.hashCode ^
       locked.hashCode ^
       memo.hashCode ^
-      idAsset.hashCode;
+      idAsset.hashCode ^
+      assetDisplay.hashCode;
 
   @override
   bool operator ==(Object other) =>
@@ -538,7 +544,8 @@ class TxNote {
           value == other.value &&
           locked == other.locked &&
           memo == other.memo &&
-          idAsset == other.idAsset;
+          idAsset == other.idAsset &&
+          assetDisplay == other.assetDisplay;
 }
 
 class TxOutput {
@@ -584,20 +591,29 @@ class TxSpend {
   final int pool;
   final int height;
   final BigInt value;
+  final int? idAsset;
+  final String assetDisplay;
 
   const TxSpend({
     required this.id,
     required this.pool,
     required this.height,
     required this.value,
+    this.idAsset,
+    required this.assetDisplay,
   });
 
   static Future<TxSpend> default_() =>
       RustLib.instance.api.crateApiAccountTxSpendDefault();
 
   @override
   int get hashCode =>
-      id.hashCode ^ pool.hashCode ^ height.hashCode ^ value.hashCode;
+      id.hashCode ^
+      pool.hashCode ^
+      height.hashCode ^
+      value.hashCode ^
+      idAsset.hashCode ^
+      assetDisplay.hashCode;
 
   @override
   bool operator ==(Object other) =>
@@ -607,5 +623,7 @@ class TxSpend {
           id == other.id &&
           pool == other.pool &&
           height == other.height &&
-          value == other.value;
+          value == other.value &&
+          idAsset == other.idAsset &&
+          assetDisplay == other.assetDisplay;
 }