Base<->Expedition ties: portal rooms, class-at-base, prep spend + Health.Max, C3/C4/Spitter (DR-046)

Portal-gated rooms: new RunLifecycle.RoomExplore loot window; room+nodes
persist past the last kill; PortalInteractRequest -> server-only PortalCommand
advances (client derives the portal pos). RunDirectorSystem moves teardown off
the InRoom edge, relocates the boss-branch/route-gate into the RoomExplore exit,
and advances an empty expedition immediately (incl. a boss clear).

Class-at-base via a shared ClassSwapUtil (meta-band strip + per-class
MetaTierState replay, so the base RPC and the dev SetClass can't drift);
ClassSelectRequest Staging-gated. Per-run PREP buffs (PrepPurchaseRequest,
PrepCatalog): once-per-run == the row's prep StatModifier band is present,
TotalOf-before-Withdraw atomic, stripped on Returning beside the boon band.

Health.Max promoted to [GhostField] (the one ghost-hash re-bake) so the boss +
floating enemy HP bars read it directly. Feel: melee cone connect-thunk (C3),
hit-stop throttle so a horde wipe can't stutter (C4), Spitter cornered-hold.

456/456 EditMode; two adversarial reviews (pre-code 13-confirmed folded;
post-impl clean bar the RoomExplore boss-clear dead-time, fixed).

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

Assets/_Project/Scripts/Simulation/World/RunRuntime.cs

@@ -48,6 +48,11 @@ namespace ProjectM.Simulation
         /// <summary>Server tick the RouteSelect grace elapses → auto-pick lowest-index reachable (NonZero; IsNewerThan-compared).</summary>
         public uint RouteGraceTick;
 
+        /// <summary>DR-046: RoomExplore soft-timeout (NonZero; auto-advance if nobody interacts the portal), so the
+        /// loot window can never softlock. Set on entering RoomExplore, compared via NetworkTick.IsNewerThan.</summary>
+        public uint ExploreGraceTick;
+
+
         // ---- boons ----
         /// <summary>Monotonic per-run boon-pick counter → distinct SourceIds in the run-scoped boon band; reset each run.</summary>
         public uint BoonPickCounter;