Retarget suspended continuations across forked SCI worlds

[whilo]

Summary

• capture SCI dynamic binding frames as explicit continuation context tokens
• retarget independent copies onto child worlds in the same lineage
• add a detached host boundary for recursively constructing independent interpreters
• document the embedding and fork semantics

Verification

• clojure -M:test:clj-test-runner (426 tests, 1663 assertions)
• focused continuation, dynamic binding, and recursive interpreter tests

[whilo]

Superseded by the continuation-context implementation already incorporated in forkable-worlds at 8ef4d70, including the opt-in runtime mode, optimization work, and cross-runtime fixes. The reviewed release increment is now tracked in #2.