Telegram Force Join Bot — PHP

Write a complete single-file PHP Telegram bot with webhook that: 1. On /start, checks if the user is a member of channels listed in CHANNELS constant using getChatMember API. 2. If not joined, shows inline keyboard with Join buttons and a Verify button. 3. On verify callback, re-checks membership and if passed, saves user to users.json with LOCK_EX. 4. Includes error handling and rate-limit protection. Provide full code with comments.