feat(algorithms): add SmsEmoa (S-Metric Selection EMOA)

Beume, Naujoks & Emmerich 2007: a steady-state MOEA that uses
hypervolume contribution as the secondary survival selection criterion.

Each generation:
- Generate ONE child via parent selection + variation + evaluation.
- Combine population + child, run non_dominated_sort.
- The discarded individual is the worst-front member with the
  smallest hypervolume contribution (computed via the new
  hypervolume_nd_from_evaluations helper).

Selection-quality is excellent at moderate objective counts (2–4) at
the cost of higher per-step compute (each survival selection requires
N+1 hypervolume evaluations of size ≤ N each). Best paired with a
tightly-bounded objective space — the user supplies a fixed reference
point in the config.

Tests: produces a non-empty front on Schaffer N.1, deterministic
reruns, panic on `population_size == 0`, panic on
`reference_point.len() != objectives.len()`.

src/algorithms/mod.rs

@@ -15,6 +15,7 @@ pub(crate) mod parallel_eval;
 pub mod particle_swarm;
 pub mod random_search;
 pub mod simulated_annealing;
+pub mod sms_emoa;
 pub mod spea2;
 pub mod tabu_search;
 pub mod umda;
@@ -33,6 +34,7 @@ pub use paes::*;
 pub use particle_swarm::*;
 pub use random_search::*;
 pub use simulated_annealing::*;
+pub use sms_emoa::*;
 pub use spea2::*;
 pub use tabu_search::*;
 pub use umda::*;