Refactor billing waiver variable names for clarity

Author: sameh-farouk

substrate-node/pallets/pallet-smart-contract/src/billing.rs

@@ -198,15 +198,15 @@ impl<T: Config> Pallet<T> {
         let seconds_elapsed =
             now.defensive_saturating_sub(contract_payment_state.last_updated_seconds);
 
-        let should_waive_payment = match &contract.contract_type {
+        let should_waive_standby_rent = match &contract.contract_type {
             types::ContractData::RentContract(rc) => {
                 let node_power = pallet_tfgrid::NodePower::<T>::get(rc.node_id);
                 node_power.is_standby()
             }
             _ => false,
         };
 
-        let should_waive_v3_billing = match &contract.contract_type {
+        let should_waive_migration_billing = match &contract.contract_type {
             types::ContractData::NodeContract(nc) => {
                 pallet_tfgrid::NodeV3BillingOptOut::<T>::contains_key(nc.node_id)
             }
@@ -216,14 +216,14 @@ impl<T: Config> Pallet<T> {
             _ => false,
         };
 
-        // For Created contracts on opted-out nodes: early return (mirrors should_waive_payment).
-        // early return is cleaner and consistent with the should_waive_payment pattern.
+        // For Created contracts on opted-out nodes: early return (mirrors should_waive_standby_rent).
+        // early return is cleaner and consistent with the should_waive_standby_rent pattern.
         // GracePeriod and Deleted fall through: zero new cost + manage_contract_state runs naturally.
-        if should_waive_v3_billing && matches!(contract.state, types::ContractState::Created) {
+        if should_waive_migration_billing && matches!(contract.state, types::ContractState::Created) {
             return Ok(().into());
         }
 
-        if should_waive_payment {
+        if should_waive_standby_rent {
             log::info!("Waiving rent for contract_id: {:?}", contract.contract_id);
             Self::deposit_event(Event::RentWaived {
                 contract_id: contract.contract_id,
@@ -236,7 +236,7 @@ impl<T: Config> Pallet<T> {
         }
 
         // Calculate the due amount
-        let (standard_amount_due, discount_received) = if should_waive_payment || should_waive_v3_billing {
+        let (standard_amount_due, discount_received) = if should_waive_standby_rent || should_waive_migration_billing {
             (BalanceOf::<T>::zero(), types::DiscountLevel::None)
         } else {
             contract
@@ -253,7 +253,7 @@ impl<T: Config> Pallet<T> {
 
         let additional_amount_due =
             if let types::ContractData::RentContract(rc) = &contract.contract_type {
-                if should_waive_payment || should_waive_v3_billing {
+                if should_waive_standby_rent || should_waive_migration_billing {
                     BalanceOf::<T>::zero()
                 } else {
                     contract.calculate_extra_fee_cost_tft(rc.node_id, seconds_elapsed)