refactor(log): migra els subsistemes restants i elimina iostream

Acaba la migració dels std::cout/cerr a Log::*:

- core/locale, core/ui/ui_config, core/rendering/{screen,text,gif,
  surface, sprite/animated_sprite, sdl3gpu/*}.
- game/{options, debug_config, editor/editor_config, levels/level_manager,
  map/{map,tilemap,paint_layer}, entities/entity_manager_loadlevel}.

Severitats coherents: warns per a configs absents amb fallback,
errors per a YAML malformat o E/S fallida, infos per a estats.

Resultat:
- 0 occurrences de std::cout/std::cerr a source/.
- Cap #include <iostream> orfà (eliminat de surface.cpp).
- Output funcional idèntic al històric; AEE_LOG filtra (ex.
  `AEE_LOG=warn` només mostra warnings, `AEE_LOG=*:warn,Tag:info`
  combina globals i overrides).

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

source/core/rendering/screen.cpp

@@ -6,13 +6,13 @@
 #include <cstddef>
 #include <cstdio>
 #include <cstdlib>
-#include <iostream>
 #include <memory>
 #include <ranges>
 
 #include "core/rendering/canvas.hpp"
 #include "core/rendering/sdl3gpu/viewport.hpp"
 #include "utils/defines.hpp"
+#include "utils/log.hpp"
 
 namespace {
 
@@ -112,11 +112,11 @@ void Screen::createSdl() {
         backend->setVSync(config_.vsync);
         if (backend->init(window_, canvas_width_, canvas_height_)) {
             gpu_driver_ = backend->getDriverName();
-            std::cout << "Screen: path GPU actiu (driver: " << gpu_driver_ << ")\n";
+            Log::info("Screen", "path GPU actiu (driver: {})", gpu_driver_);
             shader_backend_ = std::move(backend);
             return;
         }
-        std::cerr << "Screen: GPU no disponible, fallback a SDL_Renderer\n";
+        Log::warn("Screen", "GPU no disponible, fallback a SDL_Renderer");
     }
     gpu_driver_ = "sdl";