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/shared/schemas/objects/CommunicationMaxAggregateInput.schema.ts

@@ -9,6 +9,7 @@ const makeSchema = () => z.object({
   channel: z.literal(true).optional(),
   direction: z.literal(true).optional(),
   status: z.literal(true).optional(),
+  provider: z.literal(true).optional(),
   body: z.literal(true).optional(),
   callDuration: z.literal(true).optional(),
   twilioSid: z.literal(true).optional(),