Wrap fetch calls in callTelegram, callTelegramMultipart, and
downloadTelegramFile with bounded retry (max 3 attempts, 500ms/2000ms
backoff with jitter) on transient network codes and a per-attempt 15s
AbortController timeout so a stuck connection can't wedge the bridge
indefinitely. HTTP 4xx/5xx still surface as before.
Add a process-level unhandledRejection handler so a stray rejection from
a fire-and-forget void f() (e.g. timer-driven preview flush) can't crash
the host under Node 22's default unhandledRejection=throw - which is how
a remote session got dropped. Also tighten the two timer-callback voids
that can fire after their turn's try/catch is gone.
wassname