Slice Combat Depth (MC-2): enemy-variety server spine — Spitter, Swarmer, 4-type mix (DR-041)

Adds the server-authoritative mechanics for three new enemy archetypes on top of
the Grunt/Charger base, plus the weighted wave-composition that introduces them:

- Spitter: a ranged Husk variant (SpitterState) that holds a preferred range-band
  (advance/retreat/hold via EnemyAIMath.BandVelocity) and fires a telegraphed,
  dodgeable EnemyProjectile. New server EnemyProjectileMoveSystem (integrate +
  store LastStep) + EnemyProjectileDamageSystem (region-filtered swept hit-test
  rebuilt from LastStep — DR-018 anti-tunnelling; players use HitRadius, structures
  a const radius; at-most-once destroy). Concurrent-spit soft cap, soft-fail retry.
- Swarmer: marker tag + deterministic cluster spawn (1 slot = 1 pack;
  EnemyAIMath.ClusterOffset), MaxAlive counts ENTITIES so a pack defers if it
  won't fit.
- 4-type weighted mix: MixBands -> ZoneEnemyMath.WaveSlots/KindForSlot/
  PackSizeForSlot drives both the expedition director and (fork-4a) the base siege,
  with a mandatory MaxAlive cap. Legacy WaveSize/IsChargerSlot kept + parity-tested.
- Discriminator stays component-presence (no enum in Bursted systems): query-
  partition guards keep each enemy moved by exactly one EnemyAISystem pass
  (sole-Position-writer). EnemyTelegraph.IsCharger -> Kind byte for the client cue.

New authoring (Spitter/Swarmer/EnemyProjectile) + expanded director authorings with
tunable mix/cluster defaults. 13 new EditMode tests (mix composition + legacy parity,
band/cluster math, projectile move + cross-region + swept anti-tunnelling regressions);
full suite green before commit.

Dormant until the prefab/subscene wiring lands (next): the new systems guard on
TryGetSingleton/RequireForUpdate, so with no prefabs wired the new types stay inert.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/_Project/Scripts/Simulation/Combat/ZoneEnemyComponents.cs

@@ -28,6 +28,16 @@ namespace ProjectM.Simulation
         public int SpawnIntervalTicks;
         public int GruntsPerWave;
         public int ChargersPerWave;
+        // MC-2 mix bands (the director builds a ZoneEnemyMath.MixBands from these): GruntsPerWave/ChargersPerWave
+        // above are the Grunt/Charger BASE counts; these add the Spitter/Swarmer bases + per-epoch ramps + the pack.
+        public int SpitterBase;
+        public int SwarmerSlotBase;
+        public int ChargerPerEpoch;
+        public int SpitterPerEpoch;
+        public int SwarmerSlotPerEpoch;
+        public int SwarmerPackSize;       // swarmers per swarmer-slot cluster (>=1)
+        public int SwarmerPackPerEpoch;   // exposed pack ramp (v1 default 0 = fixed)
+        public float ClusterTightRadius;  // tight ring radius for a swarmer pack
         public int RewardOre;
     }