Added optional Discourse SSO.

frontend/src/pages/Login.svelte

@@ -1,13 +1,23 @@
 <script>
+  import { onMount } from 'svelte'
   import { api } from '../api.js'
   import { saveSession } from '../db.js'
 
-  let { onlogin } = $props()
+  let { onlogin, error: initialError = '' } = $props()
 
   let email = $state('')
   let password = $state('')
-  let error = $state('')
+  let error = $state(initialError)
   let loading = $state(false)
+  let ssoEnabled = $state(false)
+  let ssoLoading = $state(false)
+
+  onMount(async () => {
+    try {
+      const res = await api.sso.enabled()
+      ssoEnabled = res.enabled
+    } catch {}
+  })
 
   async function submit(e) {
     e.preventDefault()
@@ -23,6 +33,18 @@
       loading = false
     }
   }
+
+  async function startSSO() {
+    error = ''
+    ssoLoading = true
+    try {
+      const { redirect_url } = await api.sso.init()
+      window.location.href = redirect_url
+    } catch (err) {
+      error = err.message || 'SSO failed'
+      ssoLoading = false
+    }
+  }
 </script>
 
 <div class="login-wrap">
@@ -45,5 +67,28 @@
         {loading ? 'Signing in…' : 'Sign in'}
       </button>
     </form>
+    {#if ssoEnabled}
+      <div class="sso-divider"><span>or</span></div>
+      <button class="btn btn-ghost" style="width:100%" onclick={startSSO} disabled={ssoLoading}>
+        {ssoLoading ? 'Redirecting…' : 'Log in with Discourse'}
+      </button>
+    {/if}
   </div>
 </div>
+
+<style>
+  .sso-divider {
+    display: flex;
+    align-items: center;
+    margin: 1rem 0;
+    gap: 0.75rem;
+    color: var(--c-muted);
+    font-size: 0.8rem;
+  }
+  .sso-divider::before,
+  .sso-divider::after {
+    content: '';
+    flex: 1;
+    border-top: 1px solid var(--c-border);
+  }
+</style>