fix: surface errors and polish UX across Step Library and Batch pages (#92)

- StepLibraryPage: replace silent console.error with toast.error on edit/save
  failures; replace manual setTimeout toast with toast.success helper
- BatchStatusPage: add error state with retry button for failed session loads
  instead of showing ambiguous "No sessions found"
- StepDetailModal: guard clipboard copy against browser denial (no false
  "Copied!" state on permission error); fix dead "See all reviews" button
  with inline expand/collapse toggle
- StepLibraryBrowser: add "Try again" retry button to error state; retry
  increments a counter that re-triggers both load effects

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/StepLibraryPage.tsx

@@ -5,6 +5,7 @@ import { usePermissions } from '@/hooks/usePermissions'
 import { stepsApi } from '@/api/steps'
 import { StepLibraryBrowser } from '@/components/step-library/StepLibraryBrowser'
 import { StepFormModal } from '@/components/step-library/StepFormModal'
+import { toast } from '@/lib/toast'
 import type { Step, StepListItem } from '@/types/step'
 
 export default function StepLibraryPage() {
@@ -20,9 +21,6 @@ export default function StepLibraryPage() {
   const [isDeleting, setIsDeleting] = useState(false)
   const [deleteError, setDeleteError] = useState<string | null>(null)
 
-  // Toast for "Save to My Library"
-  const [saveToast, setSaveToast] = useState<string | null>(null)
-
   // Increment to trigger StepLibraryBrowser reload
   const [refreshKey, setRefreshKey] = useState(0)
   const refresh = () => setRefreshKey(k => k + 1)
@@ -32,8 +30,8 @@ export default function StepLibraryPage() {
     try {
       const full = await stepsApi.get(step.id)
       setEditingStep(full)
-    } catch (err) {
-      console.error('Failed to load step for edit:', err)
+    } catch {
+      toast.error('Failed to load step for editing')
     }
   }
 
@@ -68,11 +66,10 @@ export default function StepLibraryPage() {
         category_id: full.category_id,
         tags: full.tags,
       })
-      setSaveToast(`"${full.title}" saved to My Steps`)
-      setTimeout(() => setSaveToast(null), 3000)
+      toast.success(`"${full.title}" saved to My Steps`)
       refresh()
-    } catch (err) {
-      console.error('Failed to save step:', err)
+    } catch {
+      toast.error('Failed to save step to your library')
     }
   }
 
@@ -168,12 +165,6 @@ export default function StepLibraryPage() {
         </div>
       )}
 
-      {/* Save Toast */}
-      {saveToast && (
-        <div className="fixed bottom-6 left-1/2 z-50 -translate-x-1/2 rounded-lg border border-border bg-card px-4 py-2 text-sm text-foreground shadow-lg">
-          {saveToast}
-        </div>
-      )}
     </div>
   )
 }