Print Z_bneg as logical negation in Rust and Zig

[JasonGross]

Summary

• emit Rust Z_bneg as a zero comparison cast to the generated one-bit type
• emit Zig Z_bneg with @intFromBool
• track logical negation’s one-bit result for correct nested casts
• add focused emitter regressions and regenerate the 60 affected Rust/Zig files

This fixes the latent emitter mismatch described in Scrutineer finding #2525. Each generated artifact changes one expression line.

Testing

• opam exec --switch=rocq-9.1 -- make -j4 SKIP_BEDROCK2=1 src/Stringification/Rust.vo src/Stringification/Zig.vo
• cargo test --offline
• zig build
• zig build test
• git diff --check

The Cargo crate currently has no unit/doc tests, so Cargo validates full compilation; the exact emitted syntax is covered by the Rocq regression examples.

Authorship note: this was researched and written by an AI coding agent
(OpenAI Codex), working on Jason Gross's behalf; Jason reviews what is
posted from this account.