Split Bridge into input and dedicated execution screens, matching Swap

The single-screen design (amount input + live balance validation + submit
+ destination-wait, all in one ViewModel) was structurally fragile: the
live origin-balance observer and the amount-vs-balance validation ran in
the same reactive scope as execution, so a real successful transfer could
flash a false "insufficient balance" error the instant the balance dropped
post-submission. Patching that race (clearing the field, then an isExecuting
flag) kept fixing symptoms without addressing why the class of bug existed:
the app's own Swap flow avoids it entirely by keeping amount entry and
execution as separate screens/ViewModels, so validation code for the input
screen simply doesn't exist on the execution screen.

BridgeExecutionViewModel/Fragment now own the actual submit + destination-
wait, reached by navigating with a BridgeExecutionPayload once
BridgeViewModel.swapClicked() re-validates amount against the latest known
balance/reserve - a real confirmation gate, not just a UI button-disabled
look the domain layer never itself checked. A single BridgeExecutionState
sealed class (SubmittingOrigin/OriginFailed/WaitingForDestination/
DestinationConfirmed/DestinationPendingReview) replaces what used to be six
independently-updated LiveData flags that had to be kept in sync by hand.

Also fixed two real bugs found via live device testing with real funds:
- BridgeMultisigConstants.POLKADOT_USDT_ASSET_ID was 1 (the wallet's own
  chains.json ordinal for USDT on Polkadot Asset Hub) instead of 1984 (the
  real on-chain Assets pallet id, confirmed directly against the chain).
  getPolkadotUsdtReserve() queried asset 1, which the multisig has never
  held anything at, so the wUSDT->USDT reserve check always reported 0
  USDT available regardless of the multisig's real (and growing) holdings.
- The deposit-wait label's text was static XML, never updated on the
  success path - a genuinely completed bridge (destination balance
  confirmed, checkmark shown) still read "Waiting for confirmation..."
  forever, indistinguishable from actually being stuck. The new execution
  screen's label is driven by BridgeExecutionState instead.

app/src/main/java/io/novafoundation/nova/app/root/navigation/navigators/Navigator.kt

@@ -57,6 +57,8 @@ import io.novafoundation.nova.feature_ahm_impl.presentation.migrationDetails.Cha
 import io.novafoundation.nova.feature_ahm_impl.presentation.migrationDetails.ChainMigrationDetailsPayload
 import io.novafoundation.nova.feature_assets.presentation.AssetsRouter
 import io.novafoundation.nova.feature_assets.presentation.balance.detail.BalanceDetailFragment
+import io.novafoundation.nova.feature_assets.presentation.bridge.execution.BridgeExecutionFragment
+import io.novafoundation.nova.feature_assets.presentation.bridge.execution.BridgeExecutionPayload
 import io.novafoundation.nova.feature_assets.presentation.flow.network.NetworkFlowFragment
 import io.novafoundation.nova.feature_assets.presentation.flow.network.NetworkFlowPayload
 import io.novafoundation.nova.feature_assets.presentation.model.OperationParcelizeModel
@@ -304,6 +306,14 @@ class Navigator(
             .navigateInFirstAttachedContext()
     }
 
+    override fun openBridgeExecution(payload: BridgeExecutionPayload) {
+        val bundle = BridgeExecutionFragment.getBundle(payload)
+
+        navigationBuilder().action(R.id.action_bridge_to_execution)
+            .setArgs(bundle)
+            .navigateInFirstAttachedContext()
+    }
+
     override fun openTransferDetail(transaction: OperationParcelizeModel.Transfer) {
         val bundle = TransferDetailFragment.getBundle(transaction)
 

app/src/main/res/navigation/split_screen_nav_graph.xml

@@ -1201,8 +1201,22 @@
             app:popEnterAnim="@anim/fragment_close_enter"
             app:popExitAnim="@anim/fragment_close_exit" />
 
+        <action
+            android:id="@+id/action_bridge_to_execution"
+            app:destination="@id/bridgeExecutionFragment"
+            app:enterAnim="@anim/fragment_open_enter"
+            app:exitAnim="@anim/fragment_open_exit"
+            app:popEnterAnim="@anim/fragment_close_enter"
+            app:popExitAnim="@anim/fragment_close_exit" />
+
     </fragment>
 
+    <fragment
+        android:id="@+id/bridgeExecutionFragment"
+        android:name="io.novafoundation.nova.feature_assets.presentation.bridge.execution.BridgeExecutionFragment"
+        android:label="BridgeExecutionFragment"
+        tools:layout="@layout/fragment_bridge_execution" />
+
     <fragment
         android:id="@+id/tradeProvidersFragment"
         android:name="io.novafoundation.nova.feature_assets.presentation.trade.provider.TradeProviderListFragment"