refactor: eliminar sistema de shaders externos (ShaderManager + GpuShaderPreset)

Elimina el sistema multi-pass de shaders runtime en favor del PostFX nativo.
Queda solo el ciclo de 5 modos nativos: OFF → Vinyeta → Scanlines → Cromàtica → Complet.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CMakeLists.txt

@@ -64,61 +64,6 @@ if(NOT APPLE)
     endforeach()
 
     add_custom_target(shaders ALL DEPENDS ${SPIRV_HEADERS})
-
-    # External runtime shaders: auto-discover and compile data/shaders/**/*.vert/*.frag
-    # Output: <source>.spv alongside each source file (loaded at runtime by GpuShaderPreset)
-    file(GLOB_RECURSE DATA_SHADERS
-        "${CMAKE_SOURCE_DIR}/data/shaders/**/*.vert"
-        "${CMAKE_SOURCE_DIR}/data/shaders/**/*.frag")
-
-    set(DATA_SHADER_SPVS)
-    foreach(SHADER_FILE ${DATA_SHADERS})
-        get_filename_component(SHADER_EXT "${SHADER_FILE}" EXT)
-        if(SHADER_EXT STREQUAL ".vert")
-            set(STAGE_FLAG "-fshader-stage=vertex")
-        else()
-            set(STAGE_FLAG "-fshader-stage=fragment")
-        endif()
-        set(SPV_FILE "${SHADER_FILE}.spv")
-        add_custom_command(
-            OUTPUT "${SPV_FILE}"
-            COMMAND "${GLSLC}" ${STAGE_FLAG} -o "${SPV_FILE}" "${SHADER_FILE}"
-            DEPENDS "${SHADER_FILE}"
-            COMMENT "Compiling ${SHADER_FILE}"
-        )
-        list(APPEND DATA_SHADER_SPVS "${SPV_FILE}")
-    endforeach()
-
-    if(DATA_SHADER_SPVS)
-        add_custom_target(data_shaders ALL DEPENDS ${DATA_SHADER_SPVS})
-    endif()
-endif()
-
-# macOS: transpile .spv → .msl for GpuShaderPreset
-if(APPLE)
-    find_program(SPIRV_CROSS spirv-cross)
-    if(SPIRV_CROSS)
-        file(GLOB_RECURSE DATA_SHADER_SPVS
-            "${CMAKE_SOURCE_DIR}/data/shaders/*.vert.spv"
-            "${CMAKE_SOURCE_DIR}/data/shaders/*.frag.spv"
-        )
-        set(DATA_SHADER_MSLS)
-        foreach(SPV_FILE ${DATA_SHADER_SPVS})
-            set(MSL_FILE "${SPV_FILE}.msl")
-            add_custom_command(
-                OUTPUT "${MSL_FILE}"
-                COMMAND "${SPIRV_CROSS}" --msl --output "${MSL_FILE}" "${SPV_FILE}"
-                DEPENDS "${SPV_FILE}"
-                COMMENT "Transpiling ${SPV_FILE} to MSL"
-            )
-            list(APPEND DATA_SHADER_MSLS "${MSL_FILE}")
-        endforeach()
-        if(DATA_SHADER_MSLS)
-            add_custom_target(data_shader_msls ALL DEPENDS ${DATA_SHADER_MSLS})
-        endif()
-    else()
-        message(STATUS "spirv-cross not found — GpuShaderPreset will not work on macOS (run: brew install spirv-cross)")
-    endif()
 endif()
 
 # Archivos fuente (excluir main_old.cpp)
@@ -160,13 +105,6 @@ target_link_libraries(${PROJECT_NAME} ${LINK_LIBS})
 if(NOT APPLE)
     add_dependencies(${PROJECT_NAME} shaders)
     target_include_directories(${PROJECT_NAME} PRIVATE "${SHADER_GEN_DIR}")
-    if(TARGET data_shaders)
-        add_dependencies(${PROJECT_NAME} data_shaders)
-    endif()
-endif()
-
-if(APPLE AND TARGET data_shader_msls)
-    add_dependencies(${PROJECT_NAME} data_shader_msls)
 endif()
 
 # Tool: pack_resources