Add Node.js/Express backend with PostgreSQL and wire frontend to API

- Server: Express.js with 13 API route files (auth, regulations, contacts,
  calendar, truck stops, bridges, weigh stations, alerts, load board,
  escort locator, orders, documents, contributions)
- Database: PostgreSQL with Prisma ORM, 15 models covering all modules
- Auth: JWT + bcrypt with role-based access control (driver/carrier/escort/admin)
- Geospatial: Haversine distance filtering on truck stops, bridges, escorts
- Seed script: Imports all existing mock data (51 states, contacts, equipment,
  truck stops, bridges, weigh stations, alerts, seasonal restrictions)
- Frontend: All 10 data-driven pages now fetch from /api instead of mock-data.js
- API client (api.js): Compatibility layer that transforms API responses to
  match existing frontend rendering code, minimizing page-level changes

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

server/src/routes/calendar.js

@@ -0,0 +1,34 @@
+const express = require('express');
+const prisma = require('../config/db');
+
+const router = express.Router();
+
+// GET /api/calendar — all seasonal restrictions
+router.get('/', async (req, res, next) => {
+  try {
+    const restrictions = await prisma.seasonalRestriction.findMany({
+      include: { state: { select: { name: true, abbr: true } } },
+      orderBy: [{ startMonth: 'asc' }, { state: { name: 'asc' } }],
+    });
+    res.json(restrictions);
+  } catch (err) {
+    next(err);
+  }
+});
+
+// GET /api/calendar/:stateAbbr
+router.get('/:stateAbbr', async (req, res, next) => {
+  try {
+    const abbr = req.params.stateAbbr.toUpperCase();
+    const state = await prisma.state.findUnique({
+      where: { abbr },
+      include: { seasonalRestrictions: true },
+    });
+    if (!state) return res.status(404).json({ error: `State '${abbr}' not found.` });
+    res.json(state.seasonalRestrictions);
+  } catch (err) {
+    next(err);
+  }
+});
+
+module.exports = router;