feat: add Twilio SMS/call integration with settings, templates, and conversation history

packages/db/prisma/schema.prisma

@@ -37,6 +37,7 @@ model User {
   cloudFolders         CloudFolder[]
   cloudFiles           CloudFile[]
   communications       Communication[]
+  twilioSettings       TwilioSettings?
 }
 
 model Patient {
@@ -544,3 +545,17 @@ model PatientDocument {
   @@index([patientId])
   @@index([uploadedAt])
 }
+
+model TwilioSettings {
+  id              Int     @id @default(autoincrement())
+  userId          Int     @unique
+  accountSid      String
+  authToken       String
+  phoneNumber     String
+  greetingMessage String?
+  templates       Json?
+
+  user User @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+  @@map("twilio_settings")
+}