Fix formatting and example lint after shroud->noxis rename

- cargo fmt --all: shorter crate identifiers reflowed `use {...}` lists
- noxis/examples/dbg.rs: allow unwrap_used/expect_used (scratch harness),
  add module doc

crates/noxis-analysis/src/keep.rs

@@ -1,7 +1,7 @@
 //! Keep-правила: что нельзя переименовывать (glob-паттерны + entrypoint'ы).
 
-use regex::Regex;
 use noxis_classfile::{Attribute, Const, Program};
+use regex::Regex;
 
 use crate::entrypoints::Entrypoints;
 use noxis_core::Config;