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/routes/schedules.js

@@ -0,0 +1,54 @@
+const express = require("express");
+const router = express.Router();
+const { authMiddleware } = require("../middleware");
+const repo = require("../repo");
+
+router.patch(
+  "/driver/schedules/:scheduleId/status",
+  authMiddleware,
+  async (req, res) => {
+    const out = await repo.updateDriverScheduleStatus(req);
+    return res.status(out.statusCode).json(out.body);
+  },
+);
+
+router.get("/schedules", async (req, res) => {
+  const out = await repo.listSchedules(req);
+  return res.status(out.statusCode).json(out.body);
+});
+
+router.get("/schedules/overview", async (req, res) => {
+  const out = await repo.getSchedulesOverview(req);
+  return res.status(out.statusCode).json(out.body);
+});
+
+router.get("/schedules/recurring", async (req, res) => {
+  const out = await repo.listRecurringSchedules(req);
+  return res.status(out.statusCode).json(out.body);
+});
+
+router.get("/schedules/:scheduleId", async (req, res) => {
+  const out = await repo.getScheduleById(req);
+  return res.status(out.statusCode).json(out.body);
+});
+
+router.get("/schedules/:scheduleId/stops", async (req, res) => {
+  const out = await repo.getScheduleStops(req);
+  return res.status(out.statusCode).json(out.body);
+});
+
+router.post(
+  "/driver/schedules/:scheduleId/stops/:stopOrder/passed",
+  authMiddleware,
+  async (req, res) => {
+    const out = await repo.markStopPassed(req);
+    return res.status(out.statusCode).json(out.body);
+  },
+);
+
+router.get("/public/schedules/:scheduleId/progress", async (req, res) => {
+  const out = await repo.getPublicScheduleProgress(req);
+  return res.status(out.statusCode).json(out.body);
+});
+
+module.exports = router;