Remove potentially-failing unchecked arithmetic operations for ones which error

In response to 9.13.3.

Requires a bump to Rust 1.82 to take advantage of `Option::is_none_or`.

networks/monero/wallet/src/decoys.rs

@@ -18,7 +18,7 @@ use crate::{
 };
 
 const RECENT_WINDOW: u64 = 15;
-const BLOCKS_PER_YEAR: usize = 365 * 24 * 60 * 60 / BLOCK_TIME;
+const BLOCKS_PER_YEAR: usize = (365 * 24 * 60 * 60) / BLOCK_TIME;
 #[allow(clippy::cast_precision_loss)]
 const TIP_APPLICATION: f64 = (DEFAULT_LOCK_WINDOW * BLOCK_TIME) as f64;
 

networks/monero/wallet/src/scan.rs

@@ -232,7 +232,13 @@ impl InternalScanner {
 
         res.push(WalletOutput {
           absolute_id: AbsoluteId { transaction: tx_hash, index_in_transaction: o },
-          relative_id: RelativeId { index_on_blockchain: output_index_for_first_ringct_output + o },
+          relative_id: RelativeId {
+            index_on_blockchain: output_index_for_first_ringct_output.checked_add(o).ok_or(
+              ScanError::InvalidScannableBlock(
+                "transaction's output's index isn't representable as a u64",
+              ),
+            )?,
+          },
           data: OutputData { key: output_key, key_offset, commitment },
           metadata: Metadata {
             additional_timelock: tx.prefix().additional_timelock,

networks/monero/wallet/src/send/mod.rs

@@ -305,12 +305,13 @@ impl SignableTransaction {
       .payments
       .iter()
       .filter_map(|payment| match payment {
-        InternalPayment::Payment(_, amount) => Some(amount),
+        InternalPayment::Payment(_, amount) => Some(*amount),
         InternalPayment::Change(_) => None,
       })
-      .sum::<u64>();
+      .try_fold(0, u64::checked_add);
+    let payments_amount = payments_amount.ok_or(SendError::TooManyOutputs)?;
     let (weight, necessary_fee) = self.weight_and_necessary_fee();
-    if in_amount < (payments_amount + necessary_fee) {
+    if payments_amount.checked_add(necessary_fee).is_none_or(|total_out| in_amount < total_out) {
       Err(SendError::NotEnoughFunds {
         inputs: in_amount,
         outputs: payments_amount,