refactor(amount): keep cashu request amount as plain u64

Author: portal-wheatley

crates/portal-rest/src/handlers.rs

@@ -727,7 +727,7 @@ pub async fn request_cashu(
     let content = CashuRequestContent {
         mint_url: req.mint_url,
         unit: req.unit,
-        amount: Amount::new(req.amount),
+        amount: req.amount,
         request_id: Uuid::new_v4().to_string(),
         expires_at,
     };
@@ -1057,7 +1057,7 @@ async fn spawn_verification_token_request(
     let content = CashuRequestContent {
         mint_url: VERIFICATION_MINT_URL.to_string(),
         unit: VERIFICATION_TICKET_UNIT.to_string(),
-        amount: Amount::new(VERIFICATION_TOKEN_AMOUNT),
+        amount: VERIFICATION_TOKEN_AMOUNT,
         request_id: Uuid::new_v4().to_string(),
         expires_at,
     };

crates/portal/src/protocol/model.rs

@@ -444,7 +444,7 @@ pub mod payment {
         pub request_id: String,
         pub mint_url: String,
         pub unit: String,
-        pub amount: Amount,
+        pub amount: u64,
         pub expires_at: Timestamp,
     }