Merge rust-bitcoin/rust-bitcoin#6878: Automated nightly rustfmt (2026-09-13)

### base58/src/lib.rs
@@ -115,7 +115,8 @@ static BASE58_DIGITS: [Option<u8>; 128] = [
 fn build_base256<T: Buffer>(data: &str, scratch: &mut T) -> Result<(), Base256Error<T::Err>> {
     for d58 in data.bytes() {
         // Compute "X = X * 58 + next_digit" in base 256
-        let mut carry = BASE58_DIGITS.get(usize::from(d58))
+        let mut carry = BASE58_DIGITS
+            .get(usize::from(d58))
             .copied()
             .flatten()
             .ok_or(Base256Error::InvalidChar(InvalidCharacterError::new(d58)))

### hashes/src/hkdf/mod.rs
@@ -91,11 +91,8 @@ where
             let t = engine.finalize();
             let start_index = (counter - 1) * T::Hash::LEN;
             // Last block might not take full hash length.
-            let end_index = if counter == total_blocks {
-                okm.len()
-            } else {
-                counter * T::Hash::LEN
-            };
+            let end_index =
+                if counter == total_blocks { okm.len() } else { counter * T::Hash::LEN };
 
             okm[start_index..end_index].copy_from_slice(&t.as_ref()[0..(end_index - start_index)]);
         }

### units/src/amount/unsigned.rs
@@ -485,10 +485,12 @@ impl Amount {
 
         let sats = self.to_sat() as u128;
         match (sats * 4_000_000).checked_div(wu) {
-            Some(fee_rate) if fee_rate <= const_casts::u64_to_u128(u64::MAX) => {
-                R::Valid(FeeRate::from_sat_per_mvb(fee_rate as u64))
-            },
-            Some(_) => R::Error(E::while_doing(MathErrorKind::Overflow { op: MathOp::Div, is_negative: false })),
+            Some(fee_rate) if fee_rate <= const_casts::u64_to_u128(u64::MAX) =>
+                R::Valid(FeeRate::from_sat_per_mvb(fee_rate as u64)),
+            Some(_) => R::Error(E::while_doing(MathErrorKind::Overflow {
+                op: MathOp::Div,
+                is_negative: false,
+            })),
             None => R::Error(E::while_doing(MathErrorKind::DivByZero)),
         }
     }
@@ -522,7 +524,10 @@ impl Amount {
         if fee_rate <= const_casts::u64_to_u128(u64::MAX) {
             R::Valid(FeeRate::from_sat_per_mvb(fee_rate as u64))
         } else {
-            R::Error(E::while_doing(MathErrorKind::Overflow { op: MathOp::Div, is_negative: false }))
+            R::Error(E::while_doing(MathErrorKind::Overflow {
+                op: MathOp::Div,
+                is_negative: false,
+            }))
         }
     }
 

### units/src/fee_rate/serde.rs
@@ -43,7 +43,8 @@ pub mod as_sat_per_kwu_floor {
     #[inline]
     pub fn deserialize<'d, D: Deserializer<'d>>(d: D) -> Result<FeeRate, D::Error> {
         let sat = u64::deserialize(d)?;
-        let amt = Amount::from_sat(sat).map_err(|_| serde::de::Error::custom("amount out of range"))?;
+        let amt =
+            Amount::from_sat(sat).map_err(|_| serde::de::Error::custom("amount out of range"))?;
         Ok(FeeRate::from_per_kwu(amt))
     }