refactor: fase 5 — singletons a std::unique_ptr (elimina new/delete manual)

5 singletons afectats: Audio, Screen, Director, Resource::Cache, Resource::List.

- static T* instance → static std::unique_ptr<T> instance
- init(): new T() adoptat immediatament per unique_ptr (ownership RAII)
- destroy(): instance.reset() (sense delete manual)
- get(): retorna instance.get()
- Destructors moguts a public perquè std::default_delete hi pugui accedir
  (ctors privats + copy/move deleted → encapsulació efectiva mantinguda)

Ordre de destrucció preservat: SDL_AppQuit segueix cridant destroy() en
l'ordre invers a init() — la RAII automàtica no s'activa fins al final
del programa (LIFO de variables static).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

source/core/resources/resource_cache.cpp

@@ -20,14 +20,11 @@ extern unsigned char* LoadPalette(unsigned char* data);
 
 namespace Resource {
 
-    Cache* Cache::instance = nullptr;
+    std::unique_ptr<Cache> Cache::instance;
 
-    void Cache::init() { instance = new Cache(); }
-    void Cache::destroy() {
-        delete instance;
-        instance = nullptr;
-    }
-    auto Cache::get() -> Cache* { return instance; }
+    void Cache::init() { instance = std::unique_ptr<Cache>(new Cache()); }
+    void Cache::destroy() { instance.reset(); }
+    auto Cache::get() -> Cache* { return instance.get(); }
 
     namespace {
         auto basename(const std::string& path) -> std::string {

source/core/resources/resource_cache.hpp

@@ -3,6 +3,7 @@
 #include <SDL3/SDL.h>
 
 #include <cstddef>
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -20,6 +21,7 @@ namespace Resource {
         static void destroy();
         static auto get() -> Cache*;
 
+        ~Cache() = default;
         Cache(const Cache&) = delete;
         auto operator=(const Cache&) -> Cache& = delete;
 
@@ -39,7 +41,6 @@ namespace Resource {
 
        private:
         Cache() = default;
-        ~Cache() = default;
 
         enum class LoadStage {
             MUSICS,
@@ -66,7 +67,7 @@ namespace Resource {
         int loaded_count_{0};
         std::string current_loading_name_;
 
-        static Cache* instance;
+        static std::unique_ptr<Cache> instance;
     };
 
 }  // namespace Resource

source/core/resources/resource_list.cpp

@@ -9,19 +9,16 @@
 
 namespace Resource {
 
-    List* List::instance = nullptr;
+    std::unique_ptr<List> List::instance;
 
     void List::init(const std::string& yaml_path) {
-        instance = new List();
+        instance = std::unique_ptr<List>(new List());
         instance->loadFromYaml(yaml_path);
     }
 
-    void List::destroy() {
-        delete instance;
-        instance = nullptr;
-    }
+    void List::destroy() { instance.reset(); }
 
-    auto List::get() -> List* { return instance; }
+    auto List::get() -> List* { return instance.get(); }
 
     void List::loadFromYaml(const std::string& yaml_path) {
         auto bytes = ResourceHelper::loadFile(yaml_path);

source/core/resources/resource_list.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <memory>
 #include <string>
 #include <unordered_map>
 #include <utility>
@@ -25,6 +26,7 @@ namespace Resource {
         static void destroy();
         static auto get() -> List*;
 
+        ~List() = default;
         List(const List&) = delete;
         auto operator=(const List&) -> List& = delete;
 
@@ -44,7 +46,6 @@ namespace Resource {
         };
 
         List() = default;
-        ~List() = default;
 
         void loadFromYaml(const std::string& yaml_path);
         void loadFromString(const std::string& yaml_content);
@@ -55,7 +56,7 @@ namespace Resource {
 
         std::unordered_map<std::string, Item> file_list_;
 
-        static List* instance;
+        static std::unique_ptr<List> instance;
     };
 
 }  // namespace Resource