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/session/src/mock.rs

@@ -113,8 +113,8 @@ pub struct TestShouldEndSession;
 impl ShouldEndSession<u64> for TestShouldEndSession {
 	fn should_end_session(now: u64) -> bool {
 		let l = SessionLength::get();
-		now % l == 0 ||
-			ForceSessionEnd::mutate(|l| {
+		now % l == 0
+			|| ForceSessionEnd::mutate(|l| {
 				let r = *l;
 				*l = false;
 				r