extract shared mosis-core library from sandbox APIs

Create core/ directory with platform-agnostic sandbox components:
- Timer manager, JSON API, Crypto API, Virtual FS
- Lua sandbox, Permission gate, Audit log, Rate limiter
- Platform abstraction interfaces (IAssetInterface, IFilesystemInterface)
- Platform-agnostic logger with Android/Desktop implementations

Update designer to link against mosis-core library instead of
including sandbox sources directly.

This is the foundation for unifying the Android service and
desktop designer to share the same codebase.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

designer/CMakeLists.txt

@@ -30,7 +30,18 @@ FetchContent_MakeAvailable(rmlui)
 # Get glad include directories explicitly
 get_target_property(GLAD_INCLUDE_DIRS glad::glad INTERFACE_INCLUDE_DIRECTORIES)
 
-# Shared kernel library (platform-agnostic code from MosisService)
+#==============================================================================
+# Mosis Core Library (shared sandbox APIs)
+#==============================================================================
+add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/../core ${CMAKE_CURRENT_BINARY_DIR}/mosis-core)
+
+# Point mosis-core to use the same Lua and JSON as designer
+target_include_directories(mosis-core PUBLIC ${LUA_INCLUDE_DIR})
+target_link_libraries(mosis-core PUBLIC ${LUA_LIBRARIES})
+
+#==============================================================================
+# Mosis Kernel (RmlUi renderer - platform specific for now)
+#==============================================================================
 add_library(mosis-kernel STATIC
     ../src/main/cpp/RmlUi_Renderer_GL3.cpp
 )
@@ -55,15 +66,9 @@ target_compile_definitions(mosis-kernel PUBLIC
     RMLUI_GL3_CUSTOM_LOADER="glad_loader.h"
 )
 
-# Sandbox sources (reuse from MosisService)
-set(SANDBOX_SOURCES
-    ../src/main/cpp/sandbox/timer_manager.cpp
-    ../src/main/cpp/sandbox/json_api.cpp
-    ../src/main/cpp/sandbox/crypto_api.cpp
-    ../src/main/cpp/sandbox/virtual_fs.cpp
-)
-
-# Designer executable
+#==============================================================================
+# Designer Executable
+#==============================================================================
 add_executable(mosis-designer
     main.cpp
     src/desktop_platform.cpp
@@ -79,8 +84,6 @@ add_executable(mosis-designer
     # Local backend with input recording hooks
     src/backend/RmlUi_Backend_GLFW_GL3.cpp
     src/backend/RmlUi_Platform_GLFW.cpp
-    # Sandbox APIs
-    ${SANDBOX_SOURCES}
 )
 
 target_include_directories(mosis-designer PRIVATE
@@ -89,11 +92,14 @@ target_include_directories(mosis-designer PRIVATE
     src/backend
     ../src/main/kernel/include
     ../src/main/cpp
-    ../src/main/cpp/sandbox
+    # Core library includes
+    ../core/include
+    ../core/include/mosis/sandbox
 )
 
 target_link_libraries(mosis-designer PRIVATE
     mosis-kernel
+    mosis-core
     glad::glad
     glfw
     freetype