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.

api/routing.py

@@ -0,0 +1,85 @@
+"""
+Routing Rules API — CRUD for inbound routing rules and per-device DND.
+"""
+
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from api.deps import get_gateway
+from core.gateway import AIPSTNGateway
+from db.database import Device as DeviceDB
+from db.database import get_db
+from models.routing import (
+    RoutingRule,
+    RoutingRuleCreate,
+    RoutingRuleUpdate,
+)
+
+router = APIRouter()
+
+
+@router.get("/rules", response_model=list[RoutingRule])
+async def list_rules(gateway: AIPSTNGateway = Depends(get_gateway)):
+    if gateway._routing is None:
+        raise HTTPException(status_code=503, detail="Routing service not ready")
+    return sorted(gateway._routing.rules, key=lambda r: (r.priority, r.id))
+
+
+@router.post("/rules", response_model=RoutingRule, status_code=201)
+async def create_rule(
+    payload: RoutingRuleCreate,
+    gateway: AIPSTNGateway = Depends(get_gateway),
+):
+    if gateway._routing is None:
+        raise HTTPException(status_code=503, detail="Routing service not ready")
+    return await gateway._routing.create_rule(payload)
+
+
+@router.put("/rules/{rule_id}", response_model=RoutingRule)
+async def update_rule(
+    rule_id: str,
+    payload: RoutingRuleUpdate,
+    gateway: AIPSTNGateway = Depends(get_gateway),
+):
+    if gateway._routing is None:
+        raise HTTPException(status_code=503, detail="Routing service not ready")
+    rule = await gateway._routing.update_rule(rule_id, payload)
+    if rule is None:
+        raise HTTPException(status_code=404, detail=f"Rule {rule_id} not found")
+    return rule
+
+
+@router.delete("/rules/{rule_id}")
+async def delete_rule(
+    rule_id: str,
+    gateway: AIPSTNGateway = Depends(get_gateway),
+):
+    if gateway._routing is None:
+        raise HTTPException(status_code=503, detail="Routing service not ready")
+    ok = await gateway._routing.delete_rule(rule_id)
+    if not ok:
+        raise HTTPException(status_code=404, detail=f"Rule {rule_id} not found")
+    return {"status": "deleted", "rule_id": rule_id}
+
+
+@router.patch("/devices/{device_id}/dnd")
+async def set_device_dnd(
+    device_id: str,
+    payload: dict,
+    gateway: AIPSTNGateway = Depends(get_gateway),
+    db: AsyncSession = Depends(get_db),
+):
+    """Toggle Do-Not-Disturb on a device."""
+    enabled = bool(payload.get("enabled", True))
+    device = gateway.devices.get(device_id)
+    if not device:
+        raise HTTPException(status_code=404, detail=f"Device {device_id} not found")
+    device.dnd = enabled
+
+    result = await db.execute(select(DeviceDB).where(DeviceDB.id == device_id))
+    row = result.scalar_one_or_none()
+    if row is not None:
+        row.dnd = enabled
+
+    return {"device_id": device_id, "dnd": enabled}