feat(mc-core): ✨ Introduce deterministic ecology simulation logic with a new Seed domain and seed generation system

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

src/simulator/crates/mc-core/src/seed.rs

@@ -64,6 +64,13 @@ pub enum SeedDomain {
     /// existing worldgen ordinals stay frozen; closes the seed-domain bullet
     /// of objective p3-13b.
     Geological  = 8,
+    /// Per-turn worldsim continuous-tick RNG (population dynamics, ecosystem
+    /// succession, emergence) driven by `mc_worldsim::WorldSim::step`. Mixed
+    /// with `turn` via [`derive_step`] so each turn's ecology tick gets its own
+    /// deterministic stream and replaying the same turn reproduces it exactly.
+    /// Appended at the end of the enum so existing worldgen ordinals stay
+    /// frozen.
+    WorldsimDynamics = 9,
 }
 
 /// Derive a deterministic per-step seed for ambient encounter rolls.