Add resource program fuzz variation test

[prozacchiwawa]

Summary

• Add a compiler fuzz regression that generates and runs 1000 variations each for the assign and recurse fuzz resources.
• Build variations by replacing selected source forms with fuzzer placeholders, remembering originals, and expanding placeholders with same-kind scalar/list-preserving substitutions.
• Add minimal test module stubs for unused imports required by the assign fuzz resource under the existing test search path.
• Add classic Chialisp analogues for both reference resources and tests comparing each reference result to its classic analogue.

Testing

• cargo test classic_matches_reference -- --nocapture
• cargo test fuzz_resource_program_variations_run -- --nocapture