feat: migrate SMS/voice to Telnyx (TeXML), keep browser dial pad on Twilio

Twilio now handles only the in-browser dial pad (Access Token + browser-Device
outbound TwiML); Telnyx takes over SMS, inbound voicemail, the AI voice
conversation loop, and staff-triggered outbound calls via TeXML. Adds
TelnyxSettings model, Communication.provider discriminator, new comms/routes
modules, and a real Telnyx Settings page.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

packages/db/generated/prisma/schema.prisma

@@ -44,6 +44,7 @@ model User {
   cloudFiles           CloudFile[]
   communications       Communication[]
   twilioSettings       TwilioSettings?
+  telnyxSettings       TelnyxSettings?
   aiSettings           AiSettings?
   officeHours          OfficeHours?
   officeContact        OfficeContact?
@@ -562,6 +563,11 @@ enum CommunicationStatus {
   no_answer
 }
 
+enum CommunicationProvider {
+  twilio
+  telnyx
+}
+
 model Communication {
   id        Int  @id @default(autoincrement())
   patientId Int
@@ -570,9 +576,13 @@ model Communication {
   channel   CommunicationChannel
   direction CommunicationDirection
   status    CommunicationStatus
+  // Which platform produced twilioSid — twilio for dial-pad-originated calls,
+  // telnyx for everything else (SMS, inbound/AI voice, staff-triggered outbound calls).
+  provider  CommunicationProvider  @default(twilio)
 
   body         String?
   callDuration Int?
+  // Provider SID — Twilio MessageSid/CallSid, or Telnyx message/call id. See `provider`.
   twilioSid    String?
 
   createdAt DateTime @default(now())
@@ -606,6 +616,8 @@ model TwilioSettings {
   accountSid      String
   authToken       String
   phoneNumber     String
+  // Vestigial — inbound voice moved to Telnyx (TelnyxSettings.greetingMessage). No longer
+  // read/written; kept to avoid a destructive migration for a cosmetic cleanup.
   greetingMessage String?
   templates       Json?
 
@@ -614,6 +626,24 @@ model TwilioSettings {
   @@map("twilio_settings")
 }
 
+model TelnyxSettings {
+  id                 Int     @id @default(autoincrement())
+  userId             Int     @unique
+  apiKey             String
+  // Telnyx account SID (Mission Control Portal), required to place outbound
+  // TeXML calls via POST /texml/Accounts/{accountSid}/Calls — separate from apiKey.
+  accountSid         String?
+  phoneNumber        String
+  texmlApplicationId String?
+  messagingProfileId String?
+  webhookPublicKey   String?
+  greetingMessage    String?
+
+  user User @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+  @@map("telnyx_settings")
+}
+
 model AiSettings {
   id                Int     @id @default(autoincrement())
   userId            Int     @unique