perf: aplicar checks performance-* (91 fixes)

Cambios aplicados:
- Reemplazar std::endl con '\n' (91 casos)
  * std::endl hace flush del buffer (más lento)
  * '\n' solo inserta newline (más rápido)
  * Mejora rendimiento de logging/debug

Check excluido:
- performance-enum-size: Tamaño de enum no es crítico para rendimiento

source/core/graphics/shape_loader.cpp

@@ -17,7 +17,7 @@ std::shared_ptr<Shape> ShapeLoader::load(const std::string& filename) {
     // Check cache first
     auto it = cache_.find(filename);
     if (it != cache_.end()) {
-        std::cout << "[ShapeLoader] Cache hit: " << filename << std::endl;
+        std::cout << "[ShapeLoader] Cache hit: " << filename << '\n';
         return it->second;  // Cache hit
     }
 
@@ -33,7 +33,7 @@ std::shared_ptr<Shape> ShapeLoader::load(const std::string& filename) {
     std::vector<uint8_t> data = Resource::Helper::loadFile(normalized);
     if (data.empty()) {
         std::cerr << "[ShapeLoader] Error: no s'ha pogut carregar " << normalized
-                  << std::endl;
+                  << '\n';
         return nullptr;
     }
 
@@ -42,19 +42,19 @@ std::shared_ptr<Shape> ShapeLoader::load(const std::string& filename) {
     auto shape = std::make_shared<Shape>();
     if (!shape->parsejar_fitxer(file_content)) {
         std::cerr << "[ShapeLoader] Error: no s'ha pogut parsejar " << normalized
-                  << std::endl;
+                  << '\n';
         return nullptr;
     }
 
     // Verify shape is valid
     if (!shape->es_valida()) {
-        std::cerr << "[ShapeLoader] Error: forma invàlida " << normalized << std::endl;
+        std::cerr << "[ShapeLoader] Error: forma invàlida " << normalized << '\n';
         return nullptr;
     }
 
     // Cache and return
     std::cout << "[ShapeLoader] Carregat: " << normalized << " (" << shape->get_nom()
-              << ", " << shape->get_num_primitives() << " primitives)" << std::endl;
+              << ", " << shape->get_num_primitives() << " primitives)" << '\n';
 
     cache_[filename] = shape;
     return shape;
@@ -62,7 +62,7 @@ std::shared_ptr<Shape> ShapeLoader::load(const std::string& filename) {
 
 void ShapeLoader::clear_cache() {
     std::cout << "[ShapeLoader] Netejant caché (" << cache_.size() << " formes)"
-              << std::endl;
+              << '\n';
     cache_.clear();
 }