Created Turnpike, event attendee and volunteer management

Built after prototype, Traverse, an attendee and volunteer list
maintainer.

frontend/src/db.js

@@ -0,0 +1,49 @@
+import Dexie from 'dexie'
+
+export const db = new Dexie('turnpike')
+
+db.version(1).stores({
+  session: 'id, token, user',
+  meta: 'key',
+  event: 'id',
+  attendees: 'id, name, ticket_type, checked_in, deleted_at',
+  departments: 'id, name, deleted_at',
+  volunteers: 'id, name, department_id, checked_in, attendee_id, deleted_at',
+  shifts: 'id, department_id, day, deleted_at',
+  volunteer_shifts: '[volunteer_id+shift_id], volunteer_id, shift_id',
+  outbox: '++id, table, op, synced_at',
+})
+
+db.version(2).stores({
+  session: 'id, token, user',
+  meta: 'key',
+  event: 'id',
+  attendees: 'id, name, ticket_type, checked_in, volunteer_token, deleted_at',
+  departments: 'id, name, deleted_at',
+  volunteers: 'id, name, department_id, checked_in, attendee_id, deleted_at',
+  shifts: 'id, department_id, day, position, deleted_at',
+  volunteer_shifts: '[volunteer_id+shift_id], volunteer_id, shift_id',
+  outbox: '++id, table, op, synced_at',
+})
+
+export async function getLastSync() {
+  const m = await db.meta.get('last_sync')
+  return m?.value ?? ''
+}
+
+export async function setLastSync(ts) {
+  await db.meta.put({ key: 'last_sync', value: ts })
+}
+
+export async function getSession() {
+  return db.session.get(1)
+}
+
+export async function saveSession(token, user) {
+  await db.session.put({ id: 1, token, user })
+}
+
+export async function clearSession() {
+  await db.session.clear()
+  await db.meta.clear()
+}