Stage 5: Alembic migrations, durable call rows, one transcript truth

Alembic replaces create_all as the schema authority: async env.py
against Base.metadata (CLI and in-app entry paths share it via
config.attributes["connection"]), an autogenerated baseline of the
create_all-era schema, and init_db now runs upgrade head — stamping
the baseline first on a pre-Alembic database so existing deployments
adopt cleanly. create_all remains for tests only.

Calls are durable from the start: CallManager gains an
on_call_created hook (wired to persist_call_on_create) that inserts
an in_progress CallRecord the moment a call is created;
persist_call_on_end finalizes that same row. A SIGKILL mid-call now
leaves an in_progress row instead of erasing the call from history
(verified live against the dev database).

One transcript representation: ActiveCall.transcript_chunks holds
TranscriptEntry (t_offset_ms, speaker, text) — add_transcript stamps
real offsets from connect time, receptionist passes speaker instead
of encoding it into "caller: ..." strings, persisted chunks carry
real seek offsets, and the dead CallRecord.transcript Text column is
dropped by migration. Device.is_online migrates String → Boolean
(with a USING cast for existing rows).

Model de-triplication: CallResponse/CallStatusResponse build via
from_call classmethods (one ActiveCall→response mapping);
DeviceStatus deleted — can_receive_call is a computed field on
Device and the list endpoint returns the domain model; all row↔dict
and row↔domain mapping now lives in call_persistence.py
(record_summary/record_detail/chunk_to_dict + device row functions).

New tests/test_data_layer.py: upgrade-head-matches-models,
pre-Alembic adoption, durable in_progress rows, end-without-create
fallback, transcript offsets, consolidated response models.

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

services/receptionist.py

@@ -134,13 +134,9 @@ class ReceptionistService:
 
             transcript = await self._listen(call, sip_leg_id)
             if transcript:
-                call.transcript_chunks.append(f"caller: {transcript}")
-                await self.gateway.event_bus.publish(GatewayEvent(
-                    type=EventType.TRANSCRIPT_CHUNK,
-                    call_id=call.id,
-                    data={"text": transcript, "speaker": "caller"},
-                    message=f"📝 caller: {transcript[:80]}",
-                ))
+                await self.gateway.call_manager.add_transcript(
+                    call.id, transcript, speaker="caller"
+                )
 
             classification = await self._classify(call, transcript, routing_decision)
             call.intent = classification.get("intent")
@@ -390,7 +386,9 @@ class ReceptionistService:
                     await self._service_error(call.id, "transcription", e)
 
             if message_text:
-                call.transcript_chunks.append(f"caller_message: {message_text}")
+                await self.gateway.call_manager.add_transcript(
+                    call.id, message_text, speaker="caller"
+                )
 
             await self.gateway.event_bus.publish(GatewayEvent(
                 type=EventType.RECEPTIONIST_MESSAGE_SAVED,