Replace recursive evaluator traversal with continuation stack

[prozacchiwawa]

Summary

• model evaluator work as owned requests, typed results, and explicit boxed continuations
• run evaluator operations through one trampoline loop instead of recursive evaluator calls
• preserve the prior logical depth-limit semantics and shared mash-condition state
• remove the obsolete recursive stack-visitor module
• cover stack-limit boundaries and 10,000 nested evaluations

Testing

• cargo clippy --workspace -- -D warnings
• cargo fmt --all -- --check
• cargo check --all-targets
• cargo test tests::compiler::evaluate — 17 passed
• cargo test -- --skip compile_performance_suite — 697 passed, 0 failed, 1 ignored, 1 filtered

The repository's compile-performance test also passed in the prior CI run. The earlier Linux wheel failure was only its coverage gate reporting the now-removed unused stackvisit.rs; the earlier M1 wheel failure was toolchain setup (cargo missing), unrelated to this code.