fix: wire import chapter ingestion, live task polling, a11y labels, notification user targeting

- NewBookImporter now takes *Store instead of raw *minio.Client (same package access)
- Runner Dependencies gains ChapterIngester interface; storeImportedChapters no-op removed
- store.IngestChapters is now actually called after PDF/EPUB extraction
- BookImport and ChapterIngester wired in runner main.go
- CreateImportTask interface gains initiatorUserID param; threaded through store/asynq/handler
- domain.ImportTask gains InitiatorUserID field; parseImportTask populates it
- Runner notifies initiator (falls back to 'admin' when empty)
- UI: import task list polls every 3s while any task is pending/running
- UI: label[for] + input[id] fix for a11y warnings in admin import page

backend/internal/backend/handlers_import.go

@@ -115,7 +115,7 @@ func (s *Server) handleAdminImport(w http.ResponseWriter, r *http.Request) {
 		return -1
 	}, slug)
 
-	taskID, err := s.deps.Producer.CreateImportTask(r.Context(), slug, req.Title, req.FileType, objectKey)
+	taskID, err := s.deps.Producer.CreateImportTask(r.Context(), slug, req.Title, req.FileType, objectKey, "")
 	if err != nil {
 		jsonError(w, http.StatusInternalServerError, "create import task: "+err.Error())
 		return

backend/internal/backend/handlers_notifications.go

@@ -0,0 +1,69 @@
+package backend
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/libnovel/backend/internal/storage"
+)
+
+type notification struct {
+	ID      string `json:"id"`
+	UserID  string `json:"user_id"`
+	Title   string `json:"title"`
+	Message string `json:"message"`
+	Link    string `json:"link"`
+	Read    bool   `json:"read"`
+}
+
+func (s *Server) handleListNotifications(w http.ResponseWriter, r *http.Request) {
+	userID := r.URL.Query().Get("user_id")
+	if userID == "" {
+		jsonError(w, http.StatusBadRequest, "user_id required")
+		return
+	}
+
+	store, ok := s.deps.Producer.(*storage.Store)
+	if !ok {
+		jsonError(w, http.StatusInternalServerError, "storage not available")
+		return
+	}
+
+	items, err := store.ListNotifications(r.Context(), userID, 50)
+	if err != nil {
+		jsonError(w, http.StatusInternalServerError, "list notifications: "+err.Error())
+		return
+	}
+
+	// Parse each item as notification
+	notifications := make([]notification, 0, len(items))
+	for _, item := range items {
+		b, _ := json.Marshal(item)
+		var n notification
+		json.Unmarshal(b, &n)
+		notifications = append(notifications, n)
+	}
+
+	writeJSON(w, 0, map[string]any{"notifications": notifications})
+}
+
+func (s *Server) handleMarkNotificationRead(w http.ResponseWriter, r *http.Request) {
+	id := r.PathValue("id")
+	if id == "" {
+		jsonError(w, http.StatusBadRequest, "notification id required")
+		return
+	}
+
+	store, ok := s.deps.Producer.(*storage.Store)
+	if !ok {
+		jsonError(w, http.StatusInternalServerError, "storage not available")
+		return
+	}
+
+	if err := store.MarkNotificationRead(r.Context(), id); err != nil {
+		jsonError(w, http.StatusInternalServerError, "mark read: "+err.Error())
+		return
+	}
+
+	writeJSON(w, 0, map[string]any{"success": true})
+}