perf(bench): compute benchmarks against Rust and C

Problem

The open question is whether JavaScript with sound types, AOT and a JIT can be competitive with Rust and C, and nothing measures it. bench/ has only lexer and parser benches plus the TS checker comparison; the server benchmark in #794 covers cold start, memory and binary size, not throughput.

Evidence (origin/main @ d4b219507)

• bench/lexer_bench.zig
• bench/parser_bench.zig

Scope

• Kernels: nbody, fannkuch-redux, binary-trees, spectral-norm, mandelbrot, JSON parse/stringify, regex-redux, and an HTTP requests/s test.
• Runtimes: home run (JIT), home run with sound-mode emit, AOT TypeScript (when available), native Home, Bun, Node, Deno, Rust and C (same algorithm, idiomatic code).
• Report time, peak RSS and variance; pin versions and hardware in the output.

Acceptance criteria

• Suite checked into bench/ with a README and one command to run it.
• Results published per release (CI or scheduled job), so every sound/AOT change shows its effect.

Links

Related: #794, #815, #819 Part of #814.