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

pezkuwi/node/subsystem-bench/src/lib/mock/candidate_validation.rs

@@ -50,10 +50,11 @@ impl MockCandidateValidation {
 		loop {
 			let msg = ctx.recv().await.expect("Overseer never fails us");
 			match msg {
-				orchestra::FromOrchestra::Signal(signal) =>
+				orchestra::FromOrchestra::Signal(signal) => {
 					if signal == OverseerSignal::Conclude {
 						return;
-					},
+					}
+				},
 				orchestra::FromOrchestra::Communication { msg } => match msg {
 					CandidateValidationMessage::ValidateFromExhaustive {
 						response_sender,