Hazard: Blight geyser — permanent periodic both-sides AoE (Phase 1.5b bundle 3)

Review-first netcode slice (design review wf_900e9965-8f0 -> 11 folded;
post-impl wf_5c8299f8-299 clean). A PERMANENT periodic telegraphed AoE in
Blight-biome rooms only; one new [GhostField] uint NextEruptTick.

- Geyser component + GeyserEruptSystem (server): inverted invalid-tick guard
  (a baked-0 tick must NEVER erupt -> lazy-stamps born-correct instead of the
  party-wiping per-tick barrage), inline both-sides gather (SourceNetworkId=-1),
  reschedule = now + period (never +=), never destroyed.
- GeyserTelegraphSystem (client): absolute-tick growing warning disc +
  erupt burst on the >0->=<0 crossing, latched per NextEruptTick + arm-guard
  (never edge-detects the replicated field -> no phantom on 0->stamp /
  relevancy re-entry). Reuses ScorchDecalSystem + DynamicLightSystem.
- Seeded in RoomFieldSystem (Blight-gated on plan.Biome, born-correct staggered
  stamp from live ServerTick), GeyserFieldSpawner + authoring wired into the
  Gameplay subscene. Geyser.prefab duplicated from ResourceNode (no collider).
- BuildDisc promoted to FeedbackFx (shared with the barrel fuse ring).
- 474/474 EditMode incl. the unstamped-storm regression; live no-storm end-to-end.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Assets/_Project/Scripts/Authoring/Combat/GeyserAuthoring.cs

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+using ProjectM.Simulation;
+using Unity.Entities;
+using UnityEngine;
+
+namespace ProjectM.Authoring
+{
+    /// <summary>
+    /// Authoring for a Blight-geyser ghost prefab (ownerless interpolated — duplicate from ResourceNode.prefab so the
+    /// GhostAuthoringComponent + LinkedEntityGroup come free; keep a cosmetic vent mesh, NO physics collider — the
+    /// hazard is the AoE, you walk over it). Bakes <see cref="Geyser"/> (NextEruptTick left 0 — the server stamps it
+    /// born-correct from the live ServerTick at spawn in RoomFieldSystem; a 0 must NEVER erupt) +
+    /// <see cref="RegionTag"/>{Expedition} so GhostRelevancy scopes it to expedition players. The field spawner
+    /// overrides Position + the born-correct NextEruptTick per instance.
+    /// </summary>
+    public class GeyserAuthoring : MonoBehaviour
+    {
+        private class GeyserBaker : Baker<GeyserAuthoring>
+        {
+            public override void Bake(GeyserAuthoring authoring)
+            {
+                var entity = GetEntity(authoring, TransformUsageFlags.Dynamic);
+                AddComponent(entity, new Geyser { NextEruptTick = 0u }); // 0 = unstamped; server stamps born-correct at spawn
+                AddComponent(entity, new RegionTag { Region = RegionId.Expedition });
+            }
+        }
+    }
+}

Assets/_Project/Scripts/Authoring/Combat/GeyserAuthoring.cs.meta

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