Default managed mode to transcribe.shadowdao.com and simplify login UI

- Set default server_url to https://transcribe.shadowdao.com
- Remove Server URL field from managed mode settings (users don't need to configure it)
- Replace Register button with link to website signup page
- Add fallback to default URL in login handler for existing users with empty config

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lib/components/Settings.svelte

@@ -207,7 +207,7 @@
       },
       remote: {
         mode: remoteMode,
-        server_url: remoteServerUrl,
+        server_url: remoteServerUrl || MANAGED_SERVER_URL,
         byok_api_key: byokApiKey,
       },
       updates: {
@@ -252,28 +252,20 @@
     }
   }
 
+  const MANAGED_SERVER_URL = "https://transcribe.shadowdao.com";
+
   async function handleManagedLogin() {
     try {
       await backendStore.apiPost("/api/login", {
         email: managedEmail,
         password: managedPassword,
+        server_url: remoteServerUrl || MANAGED_SERVER_URL,
       });
     } catch (err) {
       console.error("Login failed:", err);
     }
   }
 
-  async function handleManagedRegister() {
-    try {
-      await backendStore.apiPost("/api/register", {
-        email: managedEmail,
-        password: managedPassword,
-      });
-    } catch (err) {
-      console.error("Register failed:", err);
-    }
-  }
-
   const CAPTION_SERVER = "https://caption.shadowdao.com";
 
   function generateRandomName(): string {
@@ -486,15 +478,6 @@
           </div>
         {/if}
         {#if remoteMode === "managed"}
-          <div class="field">
-            <label for="remote-url">Server URL</label>
-            <input
-              id="remote-url"
-              type="url"
-              bind:value={remoteServerUrl}
-              placeholder="wss://your-proxy.com"
-            />
-          </div>
           <div class="managed-auth">
             <div class="field">
               <label for="managed-email">Email</label>
@@ -515,8 +498,10 @@
             </div>
             <div class="auth-buttons">
               <button onclick={handleManagedLogin}>Login</button>
-              <button onclick={handleManagedRegister}>Register</button>
             </div>
+            <p style="font-size: 11px; color: var(--text-muted); margin-top: 8px;">
+              Don't have an account? <a href="https://transcribe.shadowdao.com/register.html" target="_blank" rel="noopener" style="color: var(--accent-blue);">Sign up here</a>
+            </p>
           </div>
         {/if}
       </section>