Show document-list root folder errors

[Copilot]

The document-list/sidebar could silently show a loader or fail to render when the account root folder was missing, unfindable, or not actually a folder. This makes those states visible in the sidebar.

• Root folder validation

  • Detects failed root-folder loads from the Solid resource error state.
  • Treats resolved documents without a docs array as non-folder documents.
  • Avoids rendering DocumentList until the root doc is folder-shaped.

• Visible error UI

  • Adds a reusable DocumentListError alert.
  • Shows a clear sidebar message for missing rootFolderUrl, failed lookup, or invalid root document.

<Show when={folderLoadError()} keyed fallback={/* document list */}>
  {(error) => (
    <DocumentListError message={error.message} detail={error.detail} />
  )}
</Show>

• Fixes don't silently fail to render sidebar #25

[patchcrow]

✅ Patchwork glance ready

https://patchwork-preview-56--patchwork-base.netlify.app

Patchwork from inkandswitch/patchwork.inkandswitch.com, packages from this PR at d3739c2.

build-info.json