feat(routes): add realtime estimates panel with pattern-aware styling

- New GET /api/stops/estimates endpoint (nano mode: tripId, patternId, estimate, delay only)
- useStopEstimates hook wiring estimates to routes-$id stop panel
- Pattern-aware styling: dim schedules and estimates from other patterns
- Past scheduled departures shown with strikethrough instead of hidden
- Persist selected pattern in URL hash (replace navigation, no history push)
- Fix planner arrivals using new estimates endpoint

1 files changed, 30 insertions, 0 deletions

diff --git a/src/frontend/app/api/arrivals.ts b/src/frontend/app/api/arrivals.ts
index 8ae6e78..ad99630 100644
--- a/src/frontend/app/api/arrivals.ts
+++ b/src/frontend/app/api/arrivals.ts
@@ -1,6 +1,8 @@
 import {
   StopArrivalsResponseSchema,
+  StopEstimatesResponseSchema,
   type StopArrivalsResponse,
+  type StopEstimatesResponse,
 } from "./schema";
 
 export const fetchArrivals = async (
@@ -29,3 +31,31 @@ export const fetchArrivals = async (
     throw e;
   }
 };
+
+export const fetchEstimates = async (
+  stopId: string,
+  routeId: string,
+  viaStopId?: string
+): Promise<StopEstimatesResponse> => {
+  let url = `/api/stops/estimates?stop=${encodeURIComponent(stopId)}&route=${encodeURIComponent(routeId)}`;
+  if (viaStopId) {
+    url += `&via=${encodeURIComponent(viaStopId)}`;
+  }
+
+  const resp = await fetch(url, {
+    headers: { Accept: "application/json" },
+  });
+
+  if (!resp.ok) {
+    throw new Error(`HTTP ${resp.status}: ${resp.statusText}`);
+  }
+
+  const data = await resp.json();
+  try {
+    return StopEstimatesResponseSchema.parse(data);
+  } catch (e) {
+    console.error("Zod parsing failed for estimates:", e);
+    console.log("Received data:", data);
+    throw e;
+  }
+};