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>

core/CMakeLists.txt

@@ -0,0 +1,100 @@
+cmake_minimum_required(VERSION 3.18)
+project(mosis-core VERSION 1.0.0 LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# Core library sources - portable sandbox APIs
+set(MOSIS_CORE_SOURCES
+    # Utility
+    src/logger.cpp
+
+    # Sandbox APIs (portable)
+    src/sandbox/timer_manager.cpp
+    src/sandbox/json_api.cpp
+    src/sandbox/crypto_api.cpp
+    src/sandbox/virtual_fs.cpp
+    src/sandbox/lua_sandbox.cpp
+    src/sandbox/permission_gate.cpp
+    src/sandbox/audit_log.cpp
+    src/sandbox/rate_limiter.cpp
+    src/sandbox/path_sandbox.cpp
+)
+
+# Optional sources that require additional dependencies
+if(MOSIS_ENABLE_DATABASE)
+    list(APPEND MOSIS_CORE_SOURCES src/sandbox/database_manager.cpp)
+endif()
+
+if(MOSIS_ENABLE_NETWORK)
+    list(APPEND MOSIS_CORE_SOURCES
+        src/sandbox/network_manager.cpp
+        src/sandbox/http_validator.cpp
+    )
+endif()
+
+# Create static library
+add_library(mosis-core STATIC ${MOSIS_CORE_SOURCES})
+
+# Include directories
+target_include_directories(mosis-core PUBLIC
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include/mosis>
+    $<INSTALL_INTERFACE:include>
+)
+
+# Also add internal include path for relative includes within library
+target_include_directories(mosis-core PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}/include/mosis/sandbox
+    ${CMAKE_CURRENT_SOURCE_DIR}/include/mosis/util
+    ${CMAKE_CURRENT_SOURCE_DIR}/include/mosis/apps
+)
+
+# Platform-specific definitions
+if(ANDROID)
+    target_compile_definitions(mosis-core PUBLIC MOSIS_PLATFORM_ANDROID)
+elseif(WIN32)
+    target_compile_definitions(mosis-core PUBLIC MOSIS_PLATFORM_WINDOWS)
+    # Windows crypto library
+    target_link_libraries(mosis-core PRIVATE bcrypt)
+elseif(APPLE)
+    target_compile_definitions(mosis-core PUBLIC MOSIS_PLATFORM_MACOS)
+else()
+    target_compile_definitions(mosis-core PUBLIC MOSIS_PLATFORM_LINUX)
+endif()
+
+# Lua is required - parent project must provide it
+if(TARGET lua_static)
+    target_link_libraries(mosis-core PUBLIC lua_static)
+elseif(TARGET lua)
+    target_link_libraries(mosis-core PUBLIC lua)
+else()
+    # Try to find Lua
+    find_package(Lua QUIET)
+    if(LUA_FOUND)
+        target_include_directories(mosis-core PUBLIC ${LUA_INCLUDE_DIR})
+        target_link_libraries(mosis-core PUBLIC ${LUA_LIBRARIES})
+    else()
+        message(WARNING "Lua not found - parent project must provide Lua target")
+    endif()
+endif()
+
+# JSON library (nlohmann/json - header only)
+if(TARGET nlohmann_json::nlohmann_json)
+    target_link_libraries(mosis-core PUBLIC nlohmann_json::nlohmann_json)
+else()
+    find_package(nlohmann_json QUIET)
+    if(nlohmann_json_FOUND)
+        target_link_libraries(mosis-core PUBLIC nlohmann_json::nlohmann_json)
+    endif()
+endif()
+
+# SQLite for database_manager (optional)
+if(MOSIS_ENABLE_DATABASE)
+    find_package(SQLite3 REQUIRED)
+    target_link_libraries(mosis-core PRIVATE SQLite::SQLite3)
+    target_compile_definitions(mosis-core PRIVATE MOSIS_HAS_SQLITE)
+endif()
+
+# Export compile commands for IDE support
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)