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/repo/route.js

@@ -0,0 +1,109 @@
+const db = require("../db");
+const { reportError } = require("../lib/report-error");
+
+// Per-user driving route repository methods (PostgreSQL mode; no DEV_MOCK
+// branch in the original handlers, so this is used in both modes).
+
+async function getRoute(req) {
+  try {
+    const { routeId } = req.params;
+    const userId = req.user.userId;
+
+    const result = await db.query(
+      `
+      SELECT 
+        r.id,
+        r.start_time,
+        r.end_time,
+        r.status,
+        bl.id as line_id,
+        bl.line_number,
+        bl.start_stop,
+        bl.end_stop,
+        bl.estimated_duration_minutes,
+        bl.description,
+        bt.id as bus_type_id,
+        bt.name as bus_type,
+        bt.seat_capacity,
+        bt.license_plate
+      FROM routes r
+      JOIN bus_lines bl ON r.bus_line_id = bl.id
+      JOIN bus_types bt ON r.bus_type_id = bt.id
+      WHERE r.id = $1 AND r.user_id = $2
+    `,
+      [routeId, userId],
+    );
+
+    if (result.rows.length === 0) {
+      return { statusCode: 404, body: { error: "route_not_found" } };
+    }
+
+    const row = result.rows[0];
+    const route = {
+      id: row.id,
+      startTime: row.start_time,
+      endTime: row.end_time,
+      status: row.status,
+      busLine: {
+        id: row.line_id,
+        lineNumber: row.line_number,
+        startStop: row.start_stop,
+        endStop: row.end_stop,
+        estimatedDuration: row.estimated_duration_minutes,
+        description: row.description,
+      },
+      busType: {
+        id: row.bus_type_id,
+        name: row.bus_type,
+        seatCapacity: row.seat_capacity,
+        licensePlate: row.license_plate,
+      },
+    };
+
+    return { statusCode: 200, body: { route } };
+  } catch (err) {
+    console.error(err);
+    reportError({ partofservice: `${req.method} ${req.originalUrl}`, error: err.stack || err.message });
+    return { statusCode: 500, body: { error: "internal_error", details: err.message } };
+  }
+}
+
+async function updateRouteStatus(req) {
+  try {
+    const { routeId } = req.params;
+    const { status } = req.body;
+    const userId = req.user.userId;
+
+    const validStatuses = [
+      "scheduled",
+      "in_progress",
+      "completed",
+      "cancelled",
+    ];
+    if (!validStatuses.includes(status)) {
+      return { statusCode: 400, body: { error: "invalid_status" } };
+    }
+
+    const result = await db.query(
+      `
+      UPDATE routes 
+      SET status = $1, updated_at = NOW()
+      WHERE id = $2 AND user_id = $3
+      RETURNING *
+    `,
+      [status, routeId, userId],
+    );
+
+    if (result.rows.length === 0) {
+      return { statusCode: 404, body: { error: "route_not_found" } };
+    }
+
+    return { statusCode: 200, body: { route: result.rows[0] } };
+  } catch (err) {
+    console.error(err);
+    reportError({ partofservice: `${req.method} ${req.originalUrl}`, error: err.stack || err.message });
+    return { statusCode: 500, body: { error: "internal_error", details: err.message } };
+  }
+}
+
+module.exports = { getRoute, updateRouteStatus };