Add self-hosted routing clients and distance calculator

RoutingConfig loads OSRM/OTP URLs from env vars. OSRM client uses the
/table endpoint for batch NxM distance matrices (walk/cycle). OTP client
uses GraphQL API for transit routes. POI distance calculator orchestrates
both, skipping already-computed distances and reporting progress.

rec/otp_client.py

@@ -0,0 +1,120 @@
+"""OpenTripPlanner 2.x GraphQL client for transit routing.
+
+Uses OTP's GTFS GraphQL API to compute transit routes between points.
+Since OTP has no matrix endpoint, individual requests are made with
+concurrency controlled via asyncio.Semaphore.
+"""
+import logging
+from dataclasses import dataclass
+
+import aiohttp
+
+from config.routing_config import RoutingConfig
+from rec.utils import nextMonday
+
+logger = logging.getLogger("uvicorn.error")
+
+# OTP 2.x GraphQL query for transit plan
+_PLAN_QUERY = """
+query Plan($fromLat: Float!, $fromLon: Float!, $toLat: Float!, $toLon: Float!, $dateTime: DateTime!) {
+  plan(
+    from: {lat: $fromLat, lon: $fromLon}
+    to: {lat: $toLat, lon: $toLon}
+    dateTime: $dateTime
+    transportModes: [{mode: TRANSIT}, {mode: WALK}]
+    numItineraries: 1
+  ) {
+    itineraries {
+      duration
+      walkDistance
+      legs {
+        mode
+        duration
+        distance
+      }
+    }
+  }
+}
+"""
+
+
+@dataclass(frozen=True)
+class OTPResult:
+    """Result of an OTP transit route calculation."""
+    duration_seconds: int
+    distance_meters: int
+
+
+async def otp_transit_route(
+    origin_lat: float,
+    origin_lon: float,
+    dest_lat: float,
+    dest_lon: float,
+    config: RoutingConfig,
+    session: aiohttp.ClientSession | None = None,
+) -> OTPResult | None:
+    """Compute a transit route using OTP 2.x GraphQL API.
+
+    Uses next Monday 9AM as departure time for consistent results.
+
+    Args:
+        origin_lat: Origin latitude.
+        origin_lon: Origin longitude.
+        dest_lat: Destination latitude.
+        dest_lon: Destination longitude.
+        config: Routing configuration.
+        session: Optional aiohttp session.
+
+    Returns:
+        OTPResult or None if no transit route was found.
+    """
+    url = f"{config.otp_url}/otp/gtfs/v1"
+
+    departure_time = nextMonday().isoformat()
+
+    payload = {
+        "query": _PLAN_QUERY,
+        "variables": {
+            "fromLat": origin_lat,
+            "fromLon": origin_lon,
+            "toLat": dest_lat,
+            "toLon": dest_lon,
+            "dateTime": departure_time,
+        },
+    }
+
+    should_close = session is None
+    if session is None:
+        session = aiohttp.ClientSession()
+
+    try:
+        async with session.post(url, json=payload) as resp:
+            if resp.status != 200:
+                logger.error(f"OTP returned {resp.status}: {await resp.text()}")
+                return None
+
+            data = await resp.json()
+
+        plan = data.get("data", {}).get("plan")
+        if not plan:
+            errors = data.get("errors")
+            if errors:
+                logger.warning(f"OTP GraphQL errors: {errors}")
+            return None
+
+        itineraries = plan.get("itineraries", [])
+        if not itineraries:
+            return None
+
+        best = itineraries[0]
+        total_distance = sum(
+            leg.get("distance", 0) for leg in best.get("legs", [])
+        )
+
+        return OTPResult(
+            duration_seconds=int(best["duration"]),
+            distance_meters=int(total_distance),
+        )
+    finally:
+        if should_close:
+            await session.close()