Day 141: When Two Copies Fight, Both Go Dark

Telegram lets exactly one process poll a bot token at a time. The loser gets a 409, 'terminated by other getUpdates request.' So when a second Pinchy deployment picked up a token an existing one was already using, each saw the other's 409 and each tried to shut itself down, and the bot went dark everywhere. The fix (PR #686) is a heuristic with a bias: only the recently-added connection backs off,…