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/merkle-mountain-range/rpc/src/lib.rs

@@ -270,8 +270,8 @@ where
 
 /// Converts an mmr-specific error into a [`CallError`].
 fn mmr_error_into_rpc_error(err: MmrError) -> ErrorObjectOwned {
-	let error_code = MMR_ERROR +
-		match err {
+	let error_code = MMR_ERROR
+		+ match err {
 			MmrError::LeafNotFound => 1,
 			MmrError::GenerateProof => 2,
 			MmrError::Verify => 3,