Add editor Assets watcher refresh loop

editor/src/Core/ProjectAssetWatcher.h

@@ -0,0 +1,72 @@
+#pragma once
+
+#include "Core/IEditorContext.h"
+
+#include <cstdint>
+#include <filesystem>
+#include <string>
+#include <unordered_map>
+
+namespace XCEngine {
+namespace Editor {
+
+class ProjectAssetWatcher {
+public:
+    void Attach(const std::string& projectPath);
+    void Detach();
+    void Update(IEditorContext& context, float dt);
+
+private:
+    struct AssetEntryState {
+        bool isDirectory = false;
+        std::uint64_t fileSize = 0;
+        std::uint64_t writeTime = 0;
+
+        bool operator==(const AssetEntryState& other) const {
+            return isDirectory == other.isDirectory &&
+                   fileSize == other.fileSize &&
+                   writeTime == other.writeTime;
+        }
+    };
+
+    struct ChangeStats {
+        std::uint32_t added = 0;
+        std::uint32_t modified = 0;
+        std::uint32_t removed = 0;
+
+        bool HasChanges() const {
+            return added > 0 || modified > 0 || removed > 0;
+        }
+
+        void Clear() {
+            added = 0;
+            modified = 0;
+            removed = 0;
+        }
+
+        void Accumulate(const ChangeStats& other) {
+            added += other.added;
+            modified += other.modified;
+            removed += other.removed;
+        }
+    };
+
+    using Snapshot = std::unordered_map<std::string, AssetEntryState>;
+
+    void RefreshProjectBinding(const std::string& projectPath);
+    void ScanForChanges();
+    void FlushPendingRefresh(IEditorContext& context);
+    static void BuildSnapshot(const std::filesystem::path& assetsRoot, Snapshot& outSnapshot);
+    static ChangeStats DiffSnapshots(const Snapshot& previousSnapshot, const Snapshot& currentSnapshot);
+
+    std::string m_projectPath;
+    std::filesystem::path m_assetsRoot;
+    Snapshot m_snapshot;
+    ChangeStats m_pendingChanges;
+    float m_scanCooldownSeconds = 0.0f;
+    float m_debounceSeconds = 0.0f;
+    bool m_hasPendingRefresh = false;
+};
+
+} // namespace Editor
+} // namespace XCEngine