feat: spendable reserved offchain balance lightning

TICKET: BTC-2859

Author: parvbitgo067

modules/abstract-lightning/src/codecs/api/balance.ts

@@ -27,6 +27,10 @@ export const ChannelBalance = t.strict(
     pendingOpenLocalBalance: LndAmount,
     /** Sum of local remote balances. */
     pendingOpenRemoteBalance: LndAmount,
+    /** Total reserved balance. */
+    reservedBalance: LndAmount,
+    /** Total spendable balance. */
+    spendableBalance: LndAmount,
   },
   'ChannelBalance'
 );
@@ -76,6 +80,8 @@ export const LndGetOffchainBalances = t.strict(
     inboundBalance: BigIntFromString,
     inboundPendingBalance: BigIntFromString,
     inboundUnsettledBalance: BigIntFromString,
+    reservedBalance: BigIntFromString,
+    spendableBalance: BigIntFromString,
   },
   'LndGetOffchainBalances'
 );