Use a pinia store to manage account state

Refactor the existing scattered code dealing with the account state into
a pinia store.

pages/index.vue

@@ -5,13 +5,13 @@
 			<li>
 				<NuxtLink to="/schedule">View Schedule</NuxtLink>
 			</li>
-			<li v-if="sessionStore.account?.type === 'admin' || sessionStore.account?.type === 'crew'">
+			<li v-if="accountStore.canEdit">
 				<NuxtLink to="/edit">Edit Schedule</NuxtLink>
 			</li>
-			<li v-if="sessionStore.account">
+			<li v-if="accountStore.valid">
 				<NuxtLink to="/account/settings">Account Settings</NuxtLink>
 			</li>
-			<li v-if="!sessionStore.account">
+			<li v-else>
 				<NuxtLink to="/login">Log In / Create Account</NuxtLink>
 			</li>
 		</ul>
@@ -19,5 +19,5 @@
 </template>
 
 <script lang="ts" setup>
-const sessionStore = useSessionStore();
+const accountStore = useAccountStore();
 </script>