Add voice & video calling to a React Native app FROM SCRATCH with the headless CometChat Calls SDK v5 (`@cometchat/calls-sdk-react-native@5`) — no prebuilt UI Kit. init→login→generateToken→render `<CometChatCalls.Component>`, granular event listeners, in-call actions (mute/video/layout/record/raise-hand), meet-style session rooms AND 1:1 ringing (Chat SDK signaling + Calls SDK media). Triggers: 'add calling from scratch react native', 'standalone video call RN', 'headless calls sdk react native', 'build my own call screen', 'meeting room join by session id RN', 'one-on-one ringing call without uikit RN', 'expo video call'.
