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

pezcumulus/primitives/core/src/lib.rs

@@ -353,11 +353,12 @@ impl CumulusDigestItem {
 /// well-behaving runtimes should not produce headers with more than one.
 pub fn extract_relay_parent(digest: &Digest) -> Option<relay_chain::Hash> {
 	digest.convert_first(|d| match d {
-		DigestItem::Consensus(id, val) if id == &CUMULUS_CONSENSUS_ID =>
+		DigestItem::Consensus(id, val) if id == &CUMULUS_CONSENSUS_ID => {
 			match CumulusDigestItem::decode(&mut &val[..]) {
 				Ok(CumulusDigestItem::RelayParent(hash)) => Some(hash),
 				_ => None,
-			},
+			}
+		},
 		_ => None,
 	})
 }