feat: implement basic auth workflow

app/pages/index.vue

@@ -1,22 +1,65 @@
 <template>
   <IonPage>
-    <IonHeader>
-      <IonToolbar color="primary">
-        <IonButtons slot="start">
-          <IonMenuButton />
-        </IonButtons>
-        <IonTitle>Home</IonTitle>
-      </IonToolbar>
-    </IonHeader>
-    <IonContent class="ion-padding">
-      <h2>Welcome to OYS Borrow a Boat</h2>
-    </IonContent>
+    <!-- Splash: unauthenticated -->
+    <template v-if="!user">
+      <IonContent class="splash-content">
+        <div class="splash-center">
+          <img src="/oysqn_logo.png" alt="OYS Borrow a Boat" class="splash-logo" />
+          <IonButton expand="block" router-link="/login" class="splash-btn">Log In</IonButton>
+        </div>
+      </IonContent>
+    </template>
+
+    <!-- Home: authenticated -->
+    <template v-else>
+      <IonHeader>
+        <IonToolbar color="primary">
+          <IonButtons slot="start">
+            <IonMenuButton />
+          </IonButtons>
+          <IonTitle>Home</IonTitle>
+        </IonToolbar>
+      </IonHeader>
+      <IonContent class="ion-padding">
+        <h2>Welcome to OYS Borrow a Boat</h2>
+      </IonContent>
+    </template>
   </IonPage>
 </template>
 
 <script setup lang="ts">
 import {
   IonPage, IonHeader, IonToolbar, IonTitle, IonContent,
-  IonButtons, IonMenuButton,
+  IonButtons, IonMenuButton, IonButton,
 } from '@ionic/vue'
+
+const user = useSupabaseUser()
+
+definePageMeta({ layout: false })
 </script>
+
+<style scoped>
+.splash-content {
+  --background: var(--ion-color-light);
+}
+
+.splash-center {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  height: 100%;
+  padding: 2rem;
+  gap: 2rem;
+}
+
+.splash-logo {
+  max-width: 280px;
+  width: 100%;
+}
+
+.splash-btn {
+  width: 100%;
+  max-width: 280px;
+}
+</style>

app/pages/login.vue

@@ -2,17 +2,114 @@
   <IonPage>
     <IonHeader>
       <IonToolbar color="primary">
+        <IonButtons slot="start">
+          <IonBackButton default-href="/" />
+        </IonButtons>
         <IonTitle>Sign In</IonTitle>
       </IonToolbar>
     </IonHeader>
     <IonContent class="ion-padding">
-      <!-- TODO: Auth form -->
+      <div class="login-form">
+        <template v-if="!sent">
+          <p class="ion-text-center">Enter your email address and we'll send you a sign-in link.</p>
+          <IonList>
+            <IonItem>
+              <IonLabel position="stacked">Email address</IonLabel>
+              <IonInput
+                v-model="email"
+                type="email"
+                placeholder="you@example.com"
+                autocomplete="email"
+                inputmode="email"
+                @keyup.enter="send"
+              />
+            </IonItem>
+          </IonList>
+          <IonButton
+            expand="block"
+            class="ion-margin-top"
+            :disabled="!email || loading"
+            @click="send"
+          >
+            <IonSpinner v-if="loading" name="crescent" slot="start" />
+            Send Sign-In Link
+          </IonButton>
+          <p v-if="error" class="error-text ion-text-center">{{ error }}</p>
+        </template>
+
+        <template v-else>
+          <div class="sent-state ion-text-center">
+            <IonIcon :icon="mailOutline" class="sent-icon" />
+            <h2>Check your email</h2>
+            <p>A sign-in link was sent to <strong>{{ email }}</strong>. Open it on this device to sign in.</p>
+            <IonButton fill="outline" expand="block" class="ion-margin-top" @click="reset">
+              Use a different email
+            </IonButton>
+          </div>
+        </template>
+      </div>
     </IonContent>
   </IonPage>
 </template>
 
 <script setup lang="ts">
-import { IonPage, IonHeader, IonToolbar, IonTitle, IonContent } from '@ionic/vue'
+import {
+  IonPage, IonHeader, IonToolbar, IonTitle, IonContent,
+  IonButtons, IonBackButton, IonButton, IonList, IonItem,
+  IonLabel, IonInput, IonSpinner, IonIcon,
+} from '@ionic/vue'
+import { mailOutline } from 'ionicons/icons'
+import { useAuthStore } from '~/stores/auth'
 
 definePageMeta({ layout: false })
+
+const auth = useAuthStore()
+
+const email = ref('')
+const loading = ref(false)
+const sent = ref(false)
+const error = ref('')
+
+async function send() {
+  if (!email.value || loading.value) return
+  loading.value = true
+  error.value = ''
+  try {
+    await auth.sendMagicLink(email.value.trim())
+    sent.value = true
+  } catch (e: unknown) {
+    error.value = e instanceof Error ? e.message : 'Failed to send link. Please try again.'
+  } finally {
+    loading.value = false
+  }
+}
+
+function reset() {
+  sent.value = false
+  email.value = ''
+  error.value = ''
+}
 </script>
+
+<style scoped>
+.login-form {
+  max-width: 400px;
+  margin: 2rem auto;
+}
+
+.sent-state {
+  margin-top: 4rem;
+}
+
+.sent-icon {
+  font-size: 4rem;
+  color: var(--ion-color-primary);
+  margin-bottom: 1rem;
+}
+
+.error-text {
+  color: var(--ion-color-danger);
+  font-size: 0.875rem;
+  margin-top: 0.5rem;
+}
+</style>