docs(examples): stale `--bin` in bench_suite/bench_profile/bench_embed_quality example headers

[ohdearquant]

Problem

Several benchmark example targets carry a //! header comment that invokes them with --bin <name>, but they are registered as [[example]] in crates/inference/Cargo.toml, so --bin does not resolve. This is the same class fixed for the Qwen3-Embedding-fetch-path examples in #697 (which corrected bench_embedding, bench_metal, bench_gpu); these remaining siblings are unrelated to that PR's scope and are split out here so the fix is tracked rather than scope-crept.

Verified against crates/inference/Cargo.toml — all are [[example]], not [[bin]]:

• crates/inference/examples/bench_suite.rs:7,8,9 — --bin bench_suite (×3)
• crates/inference/examples/bench_profile.rs:7 — --bin bench_profile
• crates/inference/examples/bench_embed_quality.rs:7,13 — --bin bench_embed_quality (×2; one header, one runtime eprintln)

(cli-tools.md:437's --bin bench_lora_mixture is correct — bench_lora_mixture is a [[bin]].)

Fix

Replace --bin <name> with --example <name> in each header/hint (keep the existing -p lattice-inference and --features as-is). Comment/string-only; no code change.

Acceptance

• No --bin invocation remains for any target that is an [[example]]
• grep -rn 'bin bench_' crates/inference/examples returns only genuine [[bin]] targets