Hygiene B3: single-sourcing & magic-number consolidation

- StructureCatalogAuthoring: WallCostOre -> WallCostBiomass (it bakes a Biomass cost; [FormerlySerializedAs] preserves the scene value).
- Harvester/Fabricator authoring: resource-id byte defaults reference ResourceId.Ore/.Charge instead of magic 2/4.
- RegionMath.RegionBoundaryX (= ExpeditionOffsetX*0.5) single-sources the region-flip X used by HudSystem + OnboardingSystem (was 500f in 3 places).
- CharacterComponent.DefaultGroundedSharpness single-sources the CC sharpness 15f (GetDefault, DashSystem, PlayerDeathStateSystem, PlayerCharacterAuthoring).
- InventorySlot [InternalBufferCapacity] references Tuning.InventoryMaxSlots.
- ConnectionMode enum -> byte-const class (project convention; removes the latent enum-in-Burst trap); field + one Seed() param become byte.
- Tuning.ChargerWindupTicks single-sources the Charger telegraph windup (EnemyBaker + TuningConfig.Defaults; was a bare 30 that could drift).
- (TicksPerSecond deliberately NOT added: no seconds->ticks conversion site exists; the tick-count fields are per-authoring designer tunables, so a const would be unreferenced.)

451/451 EditMode tests pass.

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

Assets/_Project/Scripts/Client/Onboarding/OnboardingSystem.cs

@@ -25,7 +25,7 @@ namespace ProjectM.Client
     [UpdateInGroup(typeof(PresentationSystemGroup))]
     public partial class OnboardingSystem : SystemBase
     {
-        const float ExpeditionRegionXMin = 500f; // player x past this = the +1000 expedition region (mirrors HudSystem)
+        const float ExpeditionRegionXMin = RegionMath.RegionBoundaryX; // player x past this = the +1000 expedition region (mirrors HudSystem)
 
         GameObject _go;
         UIDocument _doc;

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

@@ -45,7 +45,7 @@ namespace ProjectM.Client
         static readonly Color SlotSelBg = new(0.16f, 0.26f, 0.32f, 0.95f);
         static readonly Color SlotIdleBorder = new(1f, 1f, 1f, 0.08f);
         const int MaxPips = 12;
-        const float ExpeditionRegionXMin = 500f; // camera x past this = the +1000 expedition region (DR-013)
+        const float ExpeditionRegionXMin = RegionMath.RegionBoundaryX; // camera x past this = the +1000 expedition region (DR-013)
 
         GameObject _hudGo;
         UIDocument _doc;

Assets/_Project/Scripts/Client/UI/WorldLauncher.cs

@@ -102,7 +102,7 @@ namespace ProjectM.Client
             Busy = false;
         }
 
-        static void Seed(World world, ConnectionMode mode, string address, ushort port)
+        static void Seed(World world, byte mode, string address, ushort port)
         {
             if (world is not { IsCreated: true }) return;
             var em = world.EntityManager;