#351 New Built-in Tool: SMS Sending (tools.sms.send)

## Overview Implement SMS sending capability as a built-in tool, parallel to tools.email.send. ## Justification SMS is a fundamental communication channel needed by: - #347 Patient Post-Procedure Monitoring (SMS for pain level checks) - #349 Supply Chain Cold Chain Monitor (driver alerts) - Any workflow requiring mobile notifications ## Proposed API ```python tools.sms.send( to="+1234567890", message="Your pain level check: reply 1-10", provider="twilio", # or "aws_sns", "vonage" ) ``` ## Provider Support (Phase 1) - Twilio (most common) - AWS SNS (for AWS users) ## Configuration - Provider credentials via Vault secrets - Default provider in tenant config ## Why Built-in vs App? - Fundamental communication (like email) - Simple, standardized interface - No business logic variation