fix(stacks): reflect apply progress and clear the anatomy update banner (#1279)

* fix(stacks): reflect apply progress and clear the anatomy update banner

The "Update available" banner in the stack Anatomy panel ran its apply
in the background but gave no feedback: the apply button stayed idle and
the banner never went away once the update finished.

Pass an in-flight flag to the panel so the apply button disables and
shows progress while the update runs, and re-check the update preview
when the apply finishes so the banner clears on success and stays in
place when the update did not take effect.

* fix(stacks): scope the update re-check to its stack and keep the banner on refresh failure

The post-apply re-check of the Anatomy update banner tracked only the
in-flight flag, so switching stacks while the first was still updating
looked like a completion for the newly selected stack and triggered a
stray preview request that could clear that stack's valid banner. Track
the stack name alongside the flag and only re-check when the completion
belongs to the stack on screen.

Also keep the banner when the re-check itself fails (non-OK response or
network error) instead of clearing it, so a transient read failure can
no longer hide an update that may still be pending. Both failure paths
now log for diagnosis.

frontend/src/components/EditorLayout/EditorView.tsx

@@ -876,6 +876,7 @@ export function EditorView({
                         onOpenFiles={canRead ? () => { setEditingCompose(true); setActiveTab('files'); } : undefined}
                         onOpenGitSource={() => setGitSourceOpen(true)}
                         onApplyUpdate={() => { void updateStack(); }}
+                        applying={loadingAction === 'update'}
                         canEdit={can('stack:edit', 'stack', stackName)}
                         notifications={notifications}
                     />