fix: stale chunk auto-reload + image paste upload UX

- Add lazyWithRetry wrapper for all lazy-loaded routes to auto-reload
  on stale chunk errors after deploys (prevents ErrorBoundary flash)
- Show toast notification when image paste/upload fails due to storage
  not configured (503), instead of silent tiny error thumbnails
- Remove failed uploads from thumbnail strip on 503 (was showing
  confusing retry icon)
- Pass completed upload IDs in navigation state from dashboard input
- Suppress Sentry dialog for chunk load errors (deploy artifacts)

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

frontend/src/components/tree-editor/TreeEditorLayout.tsx

@@ -1,4 +1,5 @@
-import { lazy, Suspense } from 'react'
+import { Suspense } from 'react'
+import { lazyWithRetry } from '@/lib/lazyWithRetry'
 import { TreePreviewPanel } from '@/components/tree-preview/TreePreviewPanel'
 import { FlowCanvas } from './FlowCanvas'
 import { NodeEditorPanel } from './NodeEditorPanel'
@@ -8,7 +9,7 @@ import { cn } from '@/lib/utils'
 import { Spinner } from '@/components/common/Spinner'
 
 // Lazy load CodeModeEditor (Monaco is ~2MB)
-const CodeModeEditor = lazy(() =>
+const CodeModeEditor = lazyWithRetry(() =>
   import('./code-mode/CodeModeEditor').then(m => ({ default: m.CodeModeEditor }))
 )