praisonai-platform: default JWT signing secret 'dev-secret-change-me' enables token forgery

PraisonAI is a multi-agent teams system. Prior to 0.1.6, praisonai_platform/services/auth_service.py assigns the public dev-secret-change-me value to JWT_SECRET when PLATFORM_JWT_SECRET is unset, and its production guard does not run when PLATFORM_ENV is also unset because that setting defaults to dev. A remote unauthenticated attacker can mint an HS256 token with an arbitrary sub and email, and the platform's AuthService._verify_token() and get_current_user dependency accept the forged identity for protected API routes. This vulnerability is fixed in praisonai-platform 0.1.6.