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/pezframe/election-provider-multi-block/src/mock/mod.rs

@@ -285,9 +285,10 @@ impl InstantElectionProvider for MockFallback {
 		desired_targets: u32,
 	) -> Result<BoundedSupportsOf<Self>, Self::Error> {
 		match FallbackMode::get() {
-			FallbackModes::Continue =>
+			FallbackModes::Continue => {
 				crate::Continue::<Runtime>::instant_elect(voters, targets, desired_targets)
-					.map_err(|x| x.to_string()),
+					.map_err(|x| x.to_string())
+			},
 			FallbackModes::Emergency => crate::InitiateEmergencyPhase::<Runtime>::instant_elect(
 				voters,
 				targets,