fix(lite): per-address spendable honours the backend spendable flag; flag imported view-only addresses

Lite-parity audit: per-address spendableBalance was set equal to the gross balance, ignoring the backend's
per-note 'spendable' flag (spending key present AND note at/below the anchor height), and has_spending_key
was effectively always true (mapAddress never set spendabilityKnown). So the Send auto-picker could select
an address that can't fund the send, and an imported view-only (zxviews) address looked spendable.

- Parser: carry the backend per-note 'spendable' flag when present (Sapling notes; transparent utxos keep
  the confirmed/unspent rule). It can only narrow spendability, never widen it.
- Mapper: derive per-address spending-key evidence from positive signals only — a spendable note proves a
  key (spendable), a confirmed long-mature (>=100 blocks) still-non-spendable note proves view-only
  (!spendable); fresh/immature/no notes stay unknown so nothing is mislabelled.
- Controller: info.balance stays the gross sum; info.spendableBalance now counts only backend-spendable
  outputs; a tolerated partial refresh keeps the last-known spendable balance and view-only verdict.

Display/selection only — gating can only get stricter for view-only/unanchored funds; no send/sweep/encrypt
call changes. Test: testLitePerAddressSpendableAndViewOnly.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_phase4.cpp

@@ -11881,6 +11881,67 @@ void testLitePartialRefreshKeepsPriorAddressBalances()
     EXPECT_NEAR(state.z_addresses[0].balance, 1.2, 1e-9);  // preserved, not zeroed
 }
 
+// Lite per-address spendable: the backend's per-note 'spendable' flag drives spendableBalance (balance stays
+// gross), a mature non-spendable note marks the address view-only, and a partial refresh keeps both.
+void testLitePerAddressSpendableAndViewOnly()
+{
+    using namespace dragonx::wallet;
+
+    const auto parsed = parseLiteNotesResponse(std::string(R"({
+        "unspent_notes":[
+          {"address":"zsKey","created_in_txid":"a","created_in_block":100,"value":100000000,"spendable":true},
+          {"address":"zsKey","created_in_txid":"b","created_in_block":995,"value":50000000,"spendable":false},
+          {"address":"zsView","created_in_txid":"c","created_in_block":100,"value":200000000,"spendable":false},
+          {"address":"zsFresh","created_in_txid":"d","created_in_block":999,"value":30000000,"spendable":false}],
+        "utxos":[{"address":"t1x","created_in_txid":"e","created_in_block":100,"value":70000000}],
+        "pending_notes":[],"pending_utxos":[]})"));
+    EXPECT_TRUE(parsed.ok);
+    if (!parsed.ok) return;
+    EXPECT_TRUE(parsed.notes.unspentNotes[0].spendable);
+    EXPECT_FALSE(parsed.notes.unspentNotes[1].spendable);
+    EXPECT_TRUE(parsed.notes.utxos[0].spendable);   // no flag on utxos -> confirmed/unspent rule
+
+    LiteWalletRefreshBundle bundle;
+    bundle.complete = true;
+    bundle.hasAddresses = true;
+    bundle.addresses.zAddresses = {"zsKey", "zsView", "zsFresh"};
+    bundle.addresses.tAddresses = {"t1x"};
+    bundle.hasNotes = true;
+    bundle.notes = parsed.notes;
+    bundle.hasSyncStatus = true;
+    bundle.syncStatus.syncedBlocks = 1000;
+    bundle.syncStatus.totalBlocks = 1000;
+    bundle.syncStatus.complete = true;
+
+    dragonx::WalletState state;
+    applyLiteRefreshModelToWalletState(mapLiteWalletRefreshBundle(bundle).model, state);
+    EXPECT_EQ(static_cast<int>(state.z_addresses.size()), 3);
+    if (state.z_addresses.size() != 3) return;
+    const auto& key = state.z_addresses[0];
+    const auto& view = state.z_addresses[1];
+    const auto& fresh = state.z_addresses[2];
+    EXPECT_NEAR(key.balance, 1.5, 1e-9);            // gross
+    EXPECT_NEAR(key.spendableBalance, 1.0, 1e-9);   // only the anchored note
+    EXPECT_TRUE(key.has_spending_key);
+    EXPECT_NEAR(view.balance, 2.0, 1e-9);
+    EXPECT_NEAR(view.spendableBalance, 0.0, 1e-9);
+    EXPECT_FALSE(view.has_spending_key);            // mature + non-spendable => view-only
+    EXPECT_FALSE(view.isSpendable());
+    EXPECT_TRUE(fresh.has_spending_key);            // immature only => unknown, not mislabelled
+    EXPECT_NEAR(fresh.spendableBalance, 0.0, 1e-9);
+    EXPECT_NEAR(state.t_addresses[0].spendableBalance, 0.7, 1e-9);
+
+    // Partial refresh (notes failed): keep last-known balance, spendable and view-only verdict.
+    LiteWalletRefreshBundle partial;
+    partial.complete = true;
+    partial.hasAddresses = true;
+    partial.addresses.zAddresses = {"zsKey", "zsView", "zsFresh"};
+    partial.addresses.tAddresses = {"t1x"};
+    applyLiteRefreshModelToWalletState(mapLiteWalletRefreshBundle(partial).model, state);
+    EXPECT_NEAR(state.z_addresses[0].spendableBalance, 1.0, 1e-9);
+    EXPECT_FALSE(state.z_addresses[1].has_spending_key);
+}
+
 // M2b: the controller, after a wallet is ready, auto-starts sync and refreshWalletState()
 // pulls balance/addresses/transactions/syncstatus through the shared bridge into WalletState.
 void testLiteWalletControllerRefreshPopulatesState()
@@ -19526,6 +19587,7 @@ int main()
     testLiteSendAmountIsNegative();
     testLiteForeignSendFallsBackToRecordAmount();
     testLitePartialRefreshKeepsPriorAddressBalances();
+    testLitePerAddressSpendableAndViewOnly();
     testLitePerAddressBalances();
     testLiteWalletControllerNewAddress();
     testLiteSyncStatusParserRealShapes();