[fglock]

Summary

• Preserve named stash glob snapshots returned by each, including their captured CODE slot and original glob identity.
• Install copied CV slots with stash ownership accounting so module-created closures keep their captured lexical values.
• Add regression coverage for closures created in eval, copied with each, and checked for captured values and coderef identity.

Fixes #1963

Validation

• System Perl regression: 9/9 passed.
• PerlOnJava regression: 9/9 passed on JVM and interpreter.
• nice -n 19 make: passed.
• DDC::Concordance 0.50: all 26 test files and 471 tests passed on the JVM backend; all five affected test files passed on the interpreter.
• make check-links: passed.