[Epic 6.4] Implement SMS notification adapter (Twilio)

[ooples]

User Story

As a trader, I want SMS notifications so that I receive urgent alerts on my phone.

Acceptance Criteria

• SmsNotificationChannel implements INotificationChannel
• Twilio API integration via SmsOptions:
  • AccountSid (default from env: TWILIO_SID)
  • AuthToken (default from env: TWILIO_TOKEN)
  • FromNumber
  • ToNumber
• Concise message format (within SMS limits)
• Handles Twilio rate limits
• Optional: Twilio package as soft dependency

Performance Metrics

Metric	Target
Send latency	<10 seconds

Dependencies

• [Epic 6.1] Define INotificationChannel interface

NuGet Dependencies

• Twilio (optional, only needed if SMS used)