Address review: remove ENABLE_DEVELOPER_MODE guard from ProjectOptions.cmake

Requested by @lefticus in PR #144 review.

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

Author: leftibot

ProjectOptions.cmake

@@ -59,14 +59,6 @@ macro(myproject_supports_sanitizers)
 endmacro()
 
 macro(myproject_setup_options)
-  if(DEFINED ENABLE_DEVELOPER_MODE)
-    message(FATAL_ERROR
-      "ENABLE_DEVELOPER_MODE is not a valid option. "
-      "This project does not use aminya/project_options. "
-      "Developer mode is enabled when PROJECT_IS_TOP_LEVEL is set "
-      "and myproject_PACKAGING_MAINTAINER_MODE is not set.")
-  endif()
-
   option(myproject_ENABLE_HARDENING "Enable hardening" ON)
   option(myproject_ENABLE_COVERAGE "Enable coverage reporting" OFF)
   cmake_dependent_option(