feat: add call history API endpoints and TTS service client

Adds read-only access to persisted call records for the dashboard
and implements a client for the Rhema text-to-speech service.

- api/call_history.py: New router providing paged call lists
  and detailed call records with transcript metadata.
- services/tts.py: Async client for OpenAI-compatible TTS
  endpoints (Rhema/Kokoro) used for call-flow steps.

services/recording.py

@@ -138,6 +138,9 @@ class RecordingService:
         # Store metadata
         self._metadata.append(session.to_dict())
 
+        # Persist a recording row so the dashboard can find it later
+        await self._persist_recording(session)
+
         logger.info(
             f"⏹ Recording stopped: {call_id} "
             f"({session.duration_seconds}s, "
@@ -145,6 +148,29 @@ class RecordingService:
         )
         return session
 
+    @staticmethod
+    async def _persist_recording(session: "RecordingSession") -> None:
+        """Write a recordings row for this session. Failures are non-fatal."""
+        try:
+            import uuid as _uuid
+            from db.database import RecordingRecord, get_session_factory
+
+            async with get_session_factory()() as db:
+                db.add(RecordingRecord(
+                    id=f"rec_{_uuid.uuid4().hex[:10]}",
+                    call_id=session.call_id,
+                    path=session.filepath_mixed or "",
+                    format="wav",
+                    duration_s=float(session.duration_seconds or 0),
+                    size_bytes=int(session.file_size_bytes or 0),
+                    channels=1,
+                    started_at=session.started_at,
+                    ended_at=session.stopped_at,
+                ))
+                await db.commit()
+        except Exception as e:
+            logger.warning(f"Recording persistence failed: {e}")
+
     async def _recording_timeout(self, call_id: str) -> None:
         """Auto-stop recording after max duration."""
         await asyncio.sleep(self._max_recording_seconds)