afegit suport Emscripten/WebAssembly al build system

- CMakeLists.txt: branca EMSCRIPTEN amb SDL3 via FetchContent, preload de data/
  config/ i gamecontrollerdb.txt, WebGL2, EMSCRIPTEN_BUILD define i sortida .html.
  Exclou sdl3gpu_shader (no soportat a WebGL2) i el pack_tool en wasm.
- Makefile: target wasm via Docker emscripten/emsdk, build a build/wasm i
  sortida a dist/wasm (.html .js .wasm .data).
- director.cpp: createSystemFolder utilitza MEMFS en wasm (sense pwd.h/unistd.h),
  executable_path buit, dev-mode forçat (filesystem preload, no pack), windowed.
- screen.cpp: initShaders és no-op en wasm (SDL3 GPU no suportat a WebGL2).
- global_inputs.cpp: handleQuit és no-op en wasm (no es pot eixir del joc).
- Director::handleEvent ignora SDL_EVENT_QUIT en wasm.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CMakeLists.txt

@@ -127,11 +127,27 @@ set(DEBUG_SOURCES
 )
 
 # Configuración de SDL3
-find_package(SDL3 REQUIRED CONFIG REQUIRED COMPONENTS SDL3)
-message(STATUS "SDL3 encontrado: ${SDL3_INCLUDE_DIRS}")
+if(EMSCRIPTEN)
+    # En Emscripten, SDL3 se compila desde source con FetchContent
+    include(FetchContent)
+    FetchContent_Declare(
+        SDL3
+        GIT_REPOSITORY https://github.com/libsdl-org/SDL.git
+        GIT_TAG release-3.2.12
+        GIT_SHALLOW TRUE
+    )
+    set(SDL_SHARED OFF CACHE BOOL "" FORCE)
+    set(SDL_STATIC ON CACHE BOOL "" FORCE)
+    set(SDL_TEST_LIBRARY OFF CACHE BOOL "" FORCE)
+    FetchContent_MakeAvailable(SDL3)
+    message(STATUS "SDL3 compilado desde source para Emscripten")
+else()
+    find_package(SDL3 REQUIRED CONFIG REQUIRED COMPONENTS SDL3)
+    message(STATUS "SDL3 encontrado: ${SDL3_INCLUDE_DIRS}")
+endif()
 
-# --- SHADER COMPILATION (Linux/Windows only - macOS uses Metal) ---
-if(NOT APPLE)
+# --- SHADER COMPILATION (Linux/Windows only - macOS usa Metal, Emscripten no els necessita) ---
+if(NOT APPLE AND NOT EMSCRIPTEN)
     find_program(GLSLC_EXE NAMES glslc)
 
     set(SHADERS_DIR "${CMAKE_SOURCE_DIR}/data/shaders")
@@ -196,10 +212,15 @@ else()
 endif()
 
 # --- 2. AÑADIR EJECUTABLE ---
-add_executable(${PROJECT_NAME} ${APP_SOURCES} ${RENDERING_SOURCES})
+if(EMSCRIPTEN)
+    # En Emscripten no compilem sdl3gpu_shader (SDL3 GPU no està suportat a WebGL2)
+    add_executable(${PROJECT_NAME} ${APP_SOURCES})
+else()
+    add_executable(${PROJECT_NAME} ${APP_SOURCES} ${RENDERING_SOURCES})
+endif()
 
 # Shaders deben compilarse antes que el ejecutable (Linux/Windows con glslc)
-if(NOT APPLE AND GLSLC_EXE)
+if(NOT APPLE AND NOT EMSCRIPTEN AND GLSLC_EXE)
     add_dependencies(${PROJECT_NAME} shaders)
 endif()
 
@@ -243,12 +264,25 @@ elseif(APPLE)
             -rpath @executable_path/../Frameworks/
         )
     endif()
+elseif(EMSCRIPTEN)
+    target_compile_definitions(${PROJECT_NAME} PRIVATE EMSCRIPTEN_BUILD)
+    target_link_options(${PROJECT_NAME} PRIVATE
+        "SHELL:--preload-file ${CMAKE_SOURCE_DIR}/data@/data"
+        "SHELL:--preload-file ${CMAKE_SOURCE_DIR}/config@/config"
+        "SHELL:--preload-file ${CMAKE_SOURCE_DIR}/gamecontrollerdb.txt@/gamecontrollerdb.txt"
+        -sALLOW_MEMORY_GROWTH=1
+        -sMAX_WEBGL_VERSION=2
+        -sINITIAL_MEMORY=67108864
+    )
+    set_target_properties(${PROJECT_NAME} PROPERTIES SUFFIX ".html")
 elseif(UNIX AND NOT APPLE)
     target_compile_definitions(${PROJECT_NAME} PRIVATE LINUX_BUILD)
 endif()
 
-# Especificar la ubicación del ejecutable
-set_target_properties(${PROJECT_NAME} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR})
+# Especificar la ubicación del ejecutable (en desktop; a wasm queda a build/wasm/)
+if(NOT EMSCRIPTEN)
+    set_target_properties(${PROJECT_NAME} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR})
+endif()
 
 # --- 5. STATIC ANALYSIS TARGETS ---
 
@@ -315,29 +349,31 @@ else()
     message(STATUS "clang-format no encontrado - targets 'format' y 'format-check' no disponibles")
 endif()
 
-# --- 6. PACK RESOURCES TARGETS ---
-set(PACK_TOOL_SOURCES
-    ${CMAKE_SOURCE_DIR}/tools/pack_resources/pack_resources.cpp
-    ${CMAKE_SOURCE_DIR}/source/core/resources/resource_pack.cpp
-)
+# --- 6. PACK RESOURCES TARGETS (no en Emscripten: s'utilitza --preload-file) ---
+if(NOT EMSCRIPTEN)
+    set(PACK_TOOL_SOURCES
+        ${CMAKE_SOURCE_DIR}/tools/pack_resources/pack_resources.cpp
+        ${CMAKE_SOURCE_DIR}/source/core/resources/resource_pack.cpp
+    )
 
-add_executable(pack_tool ${PACK_TOOL_SOURCES})
-target_include_directories(pack_tool PRIVATE ${CMAKE_SOURCE_DIR}/source)
-set_target_properties(pack_tool PROPERTIES
-    RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/tools/pack_resources
-)
+    add_executable(pack_tool ${PACK_TOOL_SOURCES})
+    target_include_directories(pack_tool PRIVATE ${CMAKE_SOURCE_DIR}/source)
+    set_target_properties(pack_tool PROPERTIES
+        RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/tools/pack_resources
+    )
 
-file(GLOB_RECURSE DATA_FILES "${CMAKE_SOURCE_DIR}/data/*")
+    file(GLOB_RECURSE DATA_FILES "${CMAKE_SOURCE_DIR}/data/*")
 
-add_custom_command(
-    OUTPUT  "${CMAKE_SOURCE_DIR}/resources.pack"
-    COMMAND $<TARGET_FILE:pack_tool>
-            "${CMAKE_SOURCE_DIR}/data"
-            "${CMAKE_SOURCE_DIR}/resources.pack"
-    DEPENDS pack_tool ${DATA_FILES}
-    WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
-    COMMENT "Generando resources.pack desde data/..."
-)
+    add_custom_command(
+        OUTPUT  "${CMAKE_SOURCE_DIR}/resources.pack"
+        COMMAND $<TARGET_FILE:pack_tool>
+                "${CMAKE_SOURCE_DIR}/data"
+                "${CMAKE_SOURCE_DIR}/resources.pack"
+        DEPENDS pack_tool ${DATA_FILES}
+        WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
+        COMMENT "Generando resources.pack desde data/..."
+    )
 
-add_custom_target(pack DEPENDS "${CMAKE_SOURCE_DIR}/resources.pack")
-add_dependencies(${PROJECT_NAME} pack)
+    add_custom_target(pack DEPENDS "${CMAKE_SOURCE_DIR}/resources.pack")
+    add_dependencies(${PROJECT_NAME} pack)
+endif()