Hygiene B2: dead-code removal

Delete (unreferenced in any scene, per operator decision):
- TrainingDummy* chain (authoring/spawner/system/components/prefab) + UpgradePickup* chain (authoring/spawner/systems/components/prefab); remove TrainingDummyTag from the 3 live combat queries (AbilityFire/Melee/HealthApplyDamage now key on EnemyTag) and repoint HealthApplyDamageSystemTests to EnemyTag.
- Dead RPC RegionTransitSystem + RegionTransitRequest (no sender, ungated) + its test.
- Heartbeat + HeartbeatSystem (no WorldSystemFilter, ran no-op every tick) + its test.
- BuildSendSystem dead conveyor/pylon dev hooks (s_ConveyorDir, [/] rotation, Place{Pylon,Harvester,Conveyor} statics).
- Deprecated CyclePhase alias consts (Expedition/Defend/Build/*Ticks); repoint WaveSystemTests to Siege/Calm.
- Unread FeelConfig fields (HitFlashDurationMs, RumbleHeavy) + dangling HudUi doc-comments + stale crefs.

451/451 EditMode tests pass. CLAUDE.md HeartbeatSystemTests example ref to be repointed in B7.

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

Assets/_Project/Scripts/Client/Presentation/FeelConfig.cs

@@ -45,8 +45,6 @@ namespace ProjectM.Client
         public static float HitStopRefDamage;
         /// <summary>Tint for the (deferred) enemy material hit-flash — exposed now, wired in the ShaderGraph slice.</summary>
         public static Color HitFlashColor;
-        /// <summary>Duration (ms) of the deferred enemy hit-flash.</summary>
-        public static float HitFlashDurationMs;
         /// <summary>Master gate for the (deferred) true freeze-frame hit-stop. FALSE for v1 (camera-punch only).</summary>
         public static bool HitStopFreezeEnabled;
 
@@ -130,8 +128,6 @@ namespace ProjectM.Client
         public static float RumbleHit;
         /// <summary>Rumble strength on a kill.</summary>
         public static float RumbleKill;
-        /// <summary>Rumble strength on dash / local death (the heaviest).</summary>
-        public static float RumbleHeavy;
         /// <summary>Seconds a rumble pulse lasts before it auto-stops.</summary>
         public static float RumbleDurationSec;
 
@@ -190,7 +186,6 @@ namespace ProjectM.Client
             HitStopMaxFrames = 2;         // C4: a 2-frame (~33ms) camera hold reads as crunch, not a lag-y stutter
             HitStopRefDamage = 30f;
             HitFlashColor = new Color(1f, 0.85f, 0.55f, 1f);
-            HitFlashDurationMs = 80f;
             HitStopFreezeEnabled = true;  // C4: enable the finisher hit-stop hold (presentation-only camera freeze, bounded below)
 
             // Feature 1/2 death
@@ -239,7 +234,6 @@ namespace ProjectM.Client
             RumbleEnabled = true;
             RumbleHit = 0.25f;
             RumbleKill = 0.45f;
-            RumbleHeavy = 0.6f;
             RumbleDurationSec = 0.12f;
 
             // Deferred-items pass (2026-06)