Textwächter erkennt gruppierte std-Importe und globale Sperren

Mit `use std::{fs, process};` und anschließendem `fs::remove_file(…)`
kam bisher beides durch: Der Textwächter suchte `std::fs` wörtlich, und
Clippy kennt nur die aufgelisteten Funktionen. Globaler veränderlicher
Zustand über `static` mit Mutex, RwLock, OnceLock oder LazyLock wurde
auch nicht erkannt.

Neu in FORBIDDEN: `std::{` (gruppierte Importe verbergen dem Text die
Modulnamen) sowie Mutex, RwLock, OnceLock und LazyLock. Der Kern in
core/src nutzt nichts davon. Der Kommentar in core/clippy.toml behauptet
jetzt nur noch, was Clippy leistet, und CLAUDE.md nennt die Regel, dass
jeder std-Pfad in einer eigenen use-Zeile steht.

Der bestehende Selbsttest every_forbidden_term_is_detected deckt die
neuen Einträge ab.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

core/clippy.toml

@@ -1,6 +1,9 @@
-# Paths the deterministic core must never use. Clippy resolves imports, so
-# aliases and grouped imports such as `use std::{fs, env}` are caught too.
-# The text search in core/tests/forbidden_apis.rs covers the rest.
+# Paths the deterministic core must never use. Clippy resolves paths, so a
+# listed path is caught under an alias or in a grouped import as well, for
+# example `fs::read` after `use std::{fs, env}`. Only the paths listed below
+# are checked. Everything else is the job of the text search in
+# core/tests/forbidden_apis.rs, which forbids grouped imports from `std`
+# because they hide module names from it.
 
 disallowed-types = [
     { path = "std::collections::HashMap", reason = "iteration order differs between runs; use BTreeMap or Vec" },

core/tests/forbidden_apis.rs

@@ -42,12 +42,20 @@ const FORBIDDEN: &[(&str, &str)] = &[
         "the core must not read or write streams; the shell does that",
     ),
     ("std::process", "the core must not start or end processes"),
+    (
+        "std::{",
+        "grouped std imports hide forbidden modules from this search; import each path on its own line",
+    ),
     ("static mut", "global mutable state can differ between runs"),
     (
         "thread_local",
         "global mutable state can differ between runs",
     ),
     ("Atomic", "global mutable state can differ between runs"),
+    ("Mutex", "global mutable state can differ between runs"),
+    ("RwLock", "global mutable state can differ between runs"),
+    ("OnceLock", "global mutable state can differ between runs"),
+    ("LazyLock", "global mutable state can differ between runs"),
     ("unsafe", "the core forbids unsafe code"),
 ];