style: Migrate to stable-only rustfmt configuration

- Remove nightly-only features from .rustfmt.toml and vendor/ss58-registry/rustfmt.toml
- Removed features: imports_granularity, wrap_comments, comment_width,
  reorder_impl_items, spaces_around_ranges, binop_separator,
  match_arm_blocks, trailing_semicolon, trailing_comma
- Format all 898 affected files with stable rustfmt
- Ensures long-term reliability without nightly toolchain dependency

bizinikiwi/client/transaction-pool/benches/basics.rs

@@ -103,8 +103,9 @@ impl ChainApi for TestApi {
 	) -> Result<Option<NumberFor<Self::Block>>, Self::Error> {
 		Ok(match at {
 			BlockId::Number(num) => Some(*num),
-			BlockId::Hash(hash) if *hash == H256::from_low_u64_be(hash.to_low_u64_be()) =>
-				Some(hash.to_low_u64_be()),
+			BlockId::Hash(hash) if *hash == H256::from_low_u64_be(hash.to_low_u64_be()) => {
+				Some(hash.to_low_u64_be())
+			},
 			BlockId::Hash(_) => None,
 		})
 	}