[Refactor] Add folder-based namespaces to all C# scripts

Wrap all 39 scripts and 6 test files in namespaces matching their folder
structure (e.g. Assets/Scripts/Dice/ → YachtDice.Dice). Add cross-namespace
using directives where types are referenced across modules. Set rootNamespace
in both .asmdef files (YachtDice, YachtDice.Tests).

Namespace mapping:
- YachtDice.Dice — Dice, DiceRoller
- YachtDice.Economy — CurrencyBank
- YachtDice.Game — GameManager, DiceManager, DebugGameInput
- YachtDice.Inventory — InventoryController/Model/SlotView/View
- YachtDice.Modifiers — ModifierData/Effect/Enums/Pipeline/Runtime/Target
- YachtDice.Persistence — SaveData, SaveSystem
- YachtDice.Scoring — CategoryScorer, ScoreResult, ScoringSystem, YachtCategory
- YachtDice.Shop — ShopCatalog/Controller/ItemView/Model/View
- YachtDice.UI — CategoryRowView, DicePanelView, GameController, GameInfoView, ScoreCardView
- YachtDice.Editor — ModifierAssetCreator
- YachtDice.Tests — all test files

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Assets/Scripts/Scoring/CategoryScorer.cs

@@ -1,5 +1,8 @@
 using System;
 
+namespace YachtDice.Scoring
+{
+
 public static class CategoryScorer
 {
     public static int Calculate(int[] dice, YachtCategory category)
@@ -77,3 +80,4 @@ public static class CategoryScorer
         return false;
     }
 }
+}

Assets/Scripts/Scoring/ScoreResult.cs

@@ -1,6 +1,9 @@
 using System;
 using UnityEngine;
 
+namespace YachtDice.Scoring
+{
+
 [Serializable]
 public struct ScoreResult
 {
@@ -24,3 +27,4 @@ public struct ScoreResult
         };
     }
 }
+}

Assets/Scripts/Scoring/ScoringSystem.cs

@@ -1,6 +1,10 @@
 using System;
 using System.Collections.Generic;
 using UnityEngine;
+using YachtDice.Modifiers;
+
+namespace YachtDice.Scoring
+{
 
 public sealed class ScoringSystem : MonoBehaviour
 {
@@ -82,3 +86,4 @@ public sealed class ScoringSystem : MonoBehaviour
         usedCategories.Clear();
     }
 }
+}

Assets/Scripts/Scoring/YachtCategory.cs

@@ -1,3 +1,5 @@
+namespace YachtDice.Scoring
+{
 public enum YachtCategory
 {
     // Upper Section
@@ -17,3 +19,4 @@ public enum YachtCategory
     Yacht,
     Chance
 }
+}