deps: move json/httplib to CPM

cmake/dependencies/json.cmake

@@ -4,14 +4,43 @@ if(NOT YAZE_ENABLE_JSON)
   return()
 endif()
 
-message(STATUS "Setting up nlohmann_json with local ext directory")
+include(cmake/CPM.cmake)
+include(cmake/dependencies.lock)
+
+message(STATUS "Setting up nlohmann_json ${NLOHMANN_JSON_VERSION}")
+
+set(_YAZE_USE_SYSTEM_JSON ${YAZE_USE_SYSTEM_DEPS})
+
+if(NOT _YAZE_USE_SYSTEM_JSON)
+  unset(nlohmann_json_DIR CACHE)
+endif()
+
+# Try to use system packages first
+if(_YAZE_USE_SYSTEM_JSON)
+  find_package(nlohmann_json QUIET)
+  if(nlohmann_json_FOUND)
+    message(STATUS "Using system nlohmann_json")
+    set(YAZE_JSON_TARGETS nlohmann_json::nlohmann_json CACHE INTERNAL "nlohmann_json targets")
+    return()
+  elseif(YAZE_USE_SYSTEM_DEPS)
+    message(WARNING "System nlohmann_json not found despite YAZE_USE_SYSTEM_DEPS=ON; falling back to CPM download")
+  endif()
+endif()
 
-# Use the bundled nlohmann_json from ext/json
 set(JSON_BuildTests OFF CACHE BOOL "" FORCE)
 set(JSON_Install OFF CACHE BOOL "" FORCE)
 set(JSON_MultipleHeaders OFF CACHE BOOL "" FORCE)
 
-add_subdirectory(${CMAKE_SOURCE_DIR}/ext/json EXCLUDE_FROM_ALL)
+CPMAddPackage(
+  NAME nlohmann_json
+  VERSION ${NLOHMANN_JSON_VERSION}
+  GITHUB_REPOSITORY nlohmann/json
+  GIT_TAG v${NLOHMANN_JSON_VERSION}
+  OPTIONS
+    "JSON_BuildTests OFF"
+    "JSON_Install OFF"
+    "JSON_MultipleHeaders OFF"
+)
 
 # Verify target is available
 if(TARGET nlohmann_json::nlohmann_json)
@@ -21,11 +50,11 @@ elseif(TARGET nlohmann_json)
   add_library(nlohmann_json::nlohmann_json ALIAS nlohmann_json)
   message(STATUS "Created nlohmann_json::nlohmann_json alias")
 else()
-  message(FATAL_ERROR "nlohmann_json target not found after add_subdirectory")
+  message(FATAL_ERROR "nlohmann_json target not found after CPM fetch")
 endif()
 
 # Export for use in other CMake files
+set(YAZE_JSON_TARGETS nlohmann_json::nlohmann_json)
 set(YAZE_JSON_TARGETS nlohmann_json::nlohmann_json CACHE INTERNAL "nlohmann_json targets")
 
 message(STATUS "nlohmann_json setup complete")
-