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/client/bootnodes/src/advertisement.rs

@@ -441,7 +441,7 @@ impl BootnodeAdvertisement {
 
 	fn handle_dht_event(&mut self, event: DhtEvent) {
 		match event {
-			DhtEvent::StartedProviding(key) =>
+			DhtEvent::StartedProviding(key) => {
 				if Some(&key) == self.current_epoch_key.as_ref() {
 					debug!(
 						target: LOG_TARGET,
@@ -454,7 +454,8 @@ impl BootnodeAdvertisement {
 						"Successfully published provider for next epoch key {}",
 						hex::encode(key.as_ref()),
 					);
-				},
+				}
+			},
 			DhtEvent::StartProvidingFailed(key) => {
 				if Some(&key) == self.current_epoch_key.as_ref() {
 					debug!(