Module cleanup agent: forbid hoisting non-capturing lambdas into static fields

The existing rule only forbade flagging/fixing non-capturing lambdas as
allocation issues, which allowed the agent to rationalize hoisting them
into private static final fields under other justifications (e.g.,
"matching the singletons pattern"). The singleton accessor pattern in
.github/copilot-instructions.md applies to stored singleton fields like
Instrumenter, not arbitrary lambda expressions.

Tighten the rule to forbid the hoist regardless of justification, matching
the corresponding review-side guidance already in
.github/agents/knowledge/general-rules.md.

Author: trask

.github/agents/module-cleanup.agent.md

@@ -290,9 +290,13 @@ Auto-fix boundaries:
 - Never change:
   - literal type suffixes (e.g., `200` → `200L` or vice-versa) — Java widens
     automatically; both forms compile identically and the change is noise
-  - non-capturing lambdas or method references as allocation issues; do not flag,
-    fix, or justify changes to these as per-call allocations. On HotSpot /
-    OpenJDK 8+, these are cached at the call site.
+  - non-capturing lambdas or method references: never hoist an inline
+    non-capturing lambda or method reference into a `private static final` field,
+    regardless of justification (allocation, "pattern consistency", matching a
+    singletons style, or otherwise). On HotSpot / OpenJDK 8+, these are cached
+    at the `invokedynamic` call site, so the hoist is pure noise. The singleton
+    accessor pattern applies to stored singleton fields (e.g. `Instrumenter`),
+    not to arbitrary lambda expressions.
 
 Output content rules: