fix(wallet): use full URL for account data check

- Get server name from userIdServerName()
- Construct full URL to Matrix account data endpoint
- Handle 404 response to detect missing backup

features/wallet/impl/src/main/kotlin/io/element/android/features/wallet/impl/backup/WalletBackupServiceImpl.kt

@@ -11,6 +11,7 @@ import dev.zacsweers.metro.ContributesBinding
 import dev.zacsweers.metro.Inject
 import io.element.android.features.wallet.api.backup.WalletBackupService
 import io.element.android.libraries.matrix.api.MatrixClient
+import io.element.android.libraries.matrix.api.exception.ClientException
 import timber.log.Timber
 
 /**
@@ -52,22 +53,38 @@ class WalletBackupServiceImpl @Inject constructor(
 
     override suspend fun hasBackupWithoutKey(): Result<Boolean> {
         return runCatching {
-            // Build the account data URL for the wallet secret
+            // Get server name from user ID (e.g., "sulkta.com" from "@user:sulkta.com")
+            val serverName = matrixClient.userIdServerName()
             val userId = matrixClient.sessionId.value
-            val url = "/_matrix/client/v3/user/$userId/account_data/${WalletBackupService.SECRET_NAME}"
+            val secretName = WalletBackupService.SECRET_NAME
+
+            // Construct full URL to check account data
+            val url = "https://$serverName/_matrix/client/v3/user/$userId/account_data/$secretName"
+
+            Timber.d("Checking for wallet backup at: $url")
 
             try {
-                // Try to fetch the account data - if it exists, we get content back
+                // Try to fetch the account data
                 val response = matrixClient.getUrl(url).getOrThrow()
-                // If we got a non-empty response, the backup exists
-                // Even if encrypted, the account data key existing means a backup was made
                 val content = response.decodeToString()
                 Timber.d("Account data check response: ${content.take(100)}")
-                // Check if it's a valid JSON object with content (not empty {} or error)
+
+                // If we got a response with content (not empty or error), backup exists
+                // The content will be encrypted - we just need to know it exists
                 content.isNotEmpty() && content != "{}" && !content.contains("\"errcode\"")
+            } catch (e: ClientException.Generic) {
+                // Check if it's a 404 (not found)
+                if (e.message?.contains("404") == true) {
+                    Timber.d("No wallet backup found (404)")
+                    false
+                } else {
+                    Timber.w(e, "Error checking for wallet backup")
+                    // On error, assume no backup to avoid blocking setup
+                    false
+                }
             } catch (e: Exception) {
-                Timber.d(e, "Account data not found or error checking")
-                // 404 or other error means no backup exists
+                Timber.w(e, "Error checking for wallet backup")
+                // On error, assume no backup to avoid blocking setup
                 false
             }
         }