feat: import review step + admin notifications

- Import page: add file upload with review step before committing
- Backend: add analyze endpoint to preview chapters before import
- Add notifications collection + API for admin alerts
- Add bell icon in header with notification dropdown (admin only)
- Runner creates notification on import completion
- Notifications link to /admin/import for easy review

backend/internal/runner/runner.go

@@ -39,6 +39,11 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
+// Notifier creates notifications for users.
+type Notifier interface {
+	CreateNotification(ctx context.Context, userID, title, message, link string) error
+}
+
 // Config tunes the runner behaviour.
 type Config struct {
 	// WorkerID uniquely identifies this runner instance in PocketBase records.
@@ -105,6 +110,8 @@ type Dependencies struct {
 	CoverStore bookstore.CoverStore
 	// BookImport handles PDF/EPUB file parsing and chapter extraction.
 	BookImport bookstore.BookImporter
+	// Notifier creates notifications for users.
+	Notifier Notifier
 	// SearchIndex indexes books in Meilisearch after scraping.
 	// If nil a no-op is used.
 	SearchIndex meili.Client
@@ -721,6 +728,13 @@ func (r *Runner) runImportTask(ctx context.Context, task domain.ImportTask, obje
 	if err := r.deps.Consumer.FinishImportTask(ctx, task.ID, result); err != nil {
 		log.Error("runner: FinishImportTask failed", "err", err)
 	}
+
+	// Create notification for admin
+	if r.deps.Notifier != nil {
+		msg := fmt.Sprintf("Import completed: %d chapters from %s", len(chapters), task.Title)
+		_ = r.deps.Notifier.CreateNotification(ctx, "admin", "Import Complete", msg, "/admin/import")
+	}
+
 	log.Info("runner: import task finished", "chapters", len(chapters))
 }