_send_discord(), _send_slack(), and _send_twilio() all created
aiohttp.ClientSession() without a timeout, leaving HTTP requests
able to hang indefinitely. _send_whatsapp() already used
aiohttp.ClientTimeout(total=30) — this fix applies the same
pattern consistently to all platform send functions.
- Add ClientTimeout(total=30) to _send_discord() ClientSession
- Add ClientTimeout(total=30) to _send_slack() ClientSession
- Add ClientTimeout(total=30) to _send_twilio() ClientSession