perf(rust): Rewrite Rust benchmarks around shared bench.proto data

[chaokunyang]

Summary

• rewrite the Rust benchmark suite around the shared benchmarks/proto/bench.proto cases used by the C++ benchmark reference
• replace the old Rust-only benchmark model/proto tree with shared data factories plus generic Fory/Protobuf serializers and updated benchmark/report tooling
• regenerate docs/benchmarks/rust/ with the new report and plot set, removing stale old-case artifacts

Verification

• cd benchmarks/rust && cargo fmt --check
• cd benchmarks/rust && cargo test --offline
• cd benchmarks/rust && cargo bench --offline --bench serialization_bench -- struct --noplot
• cd benchmarks/rust && cargo run --offline --release --bin fory_profiler -- --print-all-serialized-sizes
• cd benchmarks/rust && CARGO_NET_OFFLINE=true bash ./run.sh