Refactor transit_api into a repo/routes module split

Split the 5,441-line index.js into an 86-line bootstrap, thin domain
route modules, shared lib/ helpers, and a repo/ layer that isolates the
DEV_MOCK branches (repo/*.mock.js). Repo methods return {statusCode, body};
routes are one-line wrappers. Pin search_path to "transit.bus" and
document the /bus/ prefix with legacy root aliases (Deprecation header).

Parity verified: 57/57 byte-identical on the stub differential harness
plus 24/24 live read-only responses vs the original against real
PostgreSQL. The only intentional behavior change: mock reorder/delete
bus-line endpoints no longer require a live DB (previously 500 in
DEV_MOCK=1 without PG). DEV_MOCK gate and node --check clean.

transit_api/mock/store.js

@@ -0,0 +1,183 @@
+// Development mock storage when DEV_MOCK=1
+const { DEV_MOCK } = require("../lib/env");
+
+const store = {
+  stops: [],
+  routeStops: [],
+  busLines: [],
+  fleetBuses: [],
+  schedules: [],
+  scheduleStopProgress: [],
+  drivers: [],
+  nextStopId: 1,
+  nextRouteStopId: 1,
+  nextBusLineId: 1,
+  nextFleetBusId: 1,
+  nextScheduleId: 1,
+  nextScheduleStopProgressId: 1,
+  nextDriverId: 1,
+};
+
+// Initialize mock drivers
+if (DEV_MOCK) {
+  store.drivers = [
+    {
+      id: 1,
+      name: "Jan Peterse",
+      email: "jan@transit.local",
+      phone: "06-12345678",
+      status: "active",
+    },
+    {
+      id: 2,
+      name: "Maria Kuijpers",
+      email: "maria@transit.local",
+      phone: "06-87654321",
+      status: "active",
+    },
+    {
+      id: 3,
+      name: "Robert Smits",
+      email: "robert@transit.local",
+      phone: "06-55555555",
+      status: "active",
+    },
+    {
+      id: 4,
+      name: "Anja Voorn",
+      email: "anja@transit.local",
+      phone: "06-44444444",
+      status: "inactive",
+    },
+  ];
+  store.nextDriverId = 5;
+
+  // Initialize test bus lines
+  store.busLines = [
+    {
+      id: 1,
+      lineNumber: 1,
+      startStop: "Central Station",
+      endStop: "Airport",
+      estimatedDurationMinutes: 45,
+      description: "Main route",
+    },
+    {
+      id: 2,
+      lineNumber: 2,
+      startStop: "Central Station",
+      endStop: "Harbor",
+      estimatedDurationMinutes: 30,
+      description: "Harbor route",
+    },
+  ];
+  store.nextBusLineId = 3;
+
+  // Initialize test stops
+  store.stops = [
+    {
+      id: 1,
+      name: "Central Station",
+      latitude: 52.0116,
+      longitude: 4.7055,
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+    },
+    {
+      id: 2,
+      name: "City Center",
+      latitude: 52.0125,
+      longitude: 4.71,
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+    },
+    {
+      id: 3,
+      name: "Airport",
+      latitude: 52.03,
+      longitude: 4.75,
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+    },
+  ];
+  store.nextStopId = 4;
+
+  // Initialize test route stops
+  store.routeStops = [
+    {
+      id: 1,
+      busLineId: 1,
+      stopId: 1,
+      stopOrder: 1,
+      estimatedArrivalMinutes: 0,
+      name: "Central Station",
+      latitude: 52.0116,
+      longitude: 4.7055,
+    },
+    {
+      id: 2,
+      busLineId: 1,
+      stopId: 2,
+      stopOrder: 2,
+      estimatedArrivalMinutes: 15,
+      name: "City Center",
+      latitude: 52.0125,
+      longitude: 4.71,
+    },
+    {
+      id: 3,
+      busLineId: 1,
+      stopId: 3,
+      stopOrder: 3,
+      estimatedArrivalMinutes: 45,
+      name: "Airport",
+      latitude: 52.03,
+      longitude: 4.75,
+    },
+  ];
+  store.nextRouteStopId = 4;
+
+  // Initialize test fleet buses
+  store.fleetBuses = [
+    {
+      id: 1,
+      name: "Bus 101",
+      seatCapacity: 45,
+      licensePlate: "AB-01-CD",
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+    },
+    {
+      id: 2,
+      name: "Bus 102",
+      seatCapacity: 50,
+      licensePlate: "AB-02-CD",
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+    },
+  ];
+  store.nextFleetBusId = 3;
+
+  // Initialize test schedule
+  const now = new Date();
+  const tomorrow = new Date(now.getTime() + 24 * 60 * 60 * 1000);
+  tomorrow.setHours(10, 0, 0, 0);
+  const endTime = new Date(tomorrow.getTime() + 45 * 60 * 1000);
+
+  store.schedules = [
+    {
+      id: 1,
+      busLineId: 1,
+      busId: 1,
+      driverId: null,
+      startTime: tomorrow.toISOString(),
+      endTime: endTime.toISOString(),
+      weekdays: [],
+      status: "planned",
+      createdAt: new Date().toISOString(),
+    },
+  ];
+  store.nextScheduleId = 2;
+}
+
+module.exports = { store };