Slice 3: Expedition Combat Spine — epoch-seeded zone waves (DR-040)

Reactivate the dormant Expedition region as a procedural combat venue.
v1 loop: walk the gate -> fight an epoch-seeded enemy wave in the
expedition -> clear -> return -> flat Ore reward (once per epoch) ->
escalated retaliation base siege.

- New sim types: ZoneEnemyTag, ZoneEnemyDirector (+ ZoneEnemyPrefab
  buffer), ZoneEnemyState, ZoneEnemyMath (grunt->charger composition
  by epoch). ZoneEnemyDirectorSystem (server, Burst): drip-spawns the
  wave at a deterministic ring under a MaxAlive cap while a player is
  out and the base is Calm; marks ClearedThisEpoch on a real clear.
  [UpdateAfter(ExpeditionFieldSystem)] only (avoids a sort cycle).
- BLOCKER 1: EnemyAISystem region-filters target selection (player +
  structure snapshots gain parallel region lists; no base structures /
  no Core fallback for expedition husks).
- BLOCKER 3: WaveSystem, ThreatDirectorSystem timeout cull, and
  CyclePhaseSystem DefendCleared + Core-breach cull all count/cull
  RegionTag{Base} husks only (the breach cull was caught region-blind
  by the post-impl review: a base breach wiped the live expedition
  wave and spuriously paid the reward).
- BLOCKER 4: reward de-duped via CycleRuntime.LastRewardedEpoch +
  ClearedThisEpoch; ExpeditionGateSystem deposits RewardOre once/epoch.
- ExpeditionFieldSystem teardown also culls zone enemies + region-
  guards the clutter loop. Subscene wired with the director + roster.

368/368 EditMode green + clean netcode Play smoke. Docs: DR-040 ->
built, session log, CLAUDE.md cross-region tag-reaudit rule.

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

Assets/_Project/Scripts/Server/World/ThreatDirectorSystem.cs

@@ -28,7 +28,6 @@ namespace ProjectM.Server
     [UpdateBefore(typeof(CyclePhaseSystem))]
     public partial struct ThreatDirectorSystem : ISystem
     {
-        EntityQuery m_Husks;
 
         [BurstCompile]
         public void OnCreate(ref SystemState state)
@@ -37,7 +36,6 @@ namespace ProjectM.Server
             state.RequireForUpdate<CycleState>();
             state.RequireForUpdate<ThreatState>();
             state.RequireForUpdate<ThreatConfig>();
-            m_Husks = state.GetEntityQuery(ComponentType.ReadOnly<EnemyTag>());
         }
 
         [BurstCompile]
@@ -109,17 +107,14 @@ namespace ProjectM.Server
                     var start = new NetworkTick(threat.SiegeStartTick);
                     if (start.IsValid && serverTick.TicksSince(start) > (int)config.SiegeTimeoutTicks)
                     {
-                        // Collapse the siege: cull every remaining Husk (a cached tag query, never RefRO on a tag).
-                        var husks = m_Husks.ToEntityArray(Allocator.Temp);
-                        if (husks.Length > 0)
-                        {
-                            var ecb = new EntityCommandBuffer(Allocator.Temp);
-                            for (int i = 0; i < husks.Length; i++)
-                                ecb.DestroyEntity(husks[i]);
-                            ecb.Playback(state.EntityManager);
-                            ecb.Dispose();
-                        }
-                        husks.Dispose();
+                        // Collapse the siege: cull every remaining BASE Husk only (expedition zone enemies are also
+                        // EnemyTag but RegionTag{Expedition}; the timeout must not destroy them — DR-040 BLOCKER 3).
+                        var ecb = new EntityCommandBuffer(Allocator.Temp);
+                        foreach (var (hr, he) in SystemAPI.Query<RefRO<RegionTag>>().WithAll<EnemyTag>().WithEntityAccess())
+                            if (hr.ValueRO.Region == RegionId.Base)
+                                ecb.DestroyEntity(he);
+                        ecb.Playback(state.EntityManager);
+                        ecb.Dispose();
 
                         if (SystemAPI.TryGetSingletonEntity<WaveState>(out var waveEntity))
                         {