fix(import): persist object_key + metadata; add nav + logout session cleanup

- Import task: persist object_key, author, cover_url, genres, summary,
  book_status in PocketBase so the runner can fetch the file and write
  book metadata on completion
- Runner poll mode: pass task.ObjectKey instead of empty string
- Runner: write BookMeta + UpsertBook in Meilisearch after chapter ingest
  so imported books appear in catalogue and search
- Import UI: add author, cover URL, genres, summary, status fields; add
  AI tasks panel (chapter names, description, image gen, tagline) after
  import completes; add AI tasks button on each done task in the list
- Admin nav: add Notifications entry to sidebar (all 5 locales)
- Logout: delete user_sessions row on sign-out so sessions don't
  accumulate as phantoms after each login/logout cycle

backend/internal/storage/store.go

@@ -647,17 +647,25 @@ func (s *Store) CreateTranslationTask(ctx context.Context, slug string, chapter
 	return rec.ID, nil
 }
 
-func (s *Store) CreateImportTask(ctx context.Context, slug, title, fileType, objectKey, initiatorUserID string) (string, error) {
+func (s *Store) CreateImportTask(ctx context.Context, task domain.ImportTask) (string, error) {
 	payload := map[string]any{
-		"slug":              slug,
-		"title":             title,
-		"file_name":         slug + "." + fileType,
-		"file_type":         fileType,
+		"slug":              task.Slug,
+		"title":             task.Title,
+		"file_name":         task.Slug + "." + task.FileType,
+		"file_type":         task.FileType,
+		"object_key":        task.ObjectKey,
+		"author":            task.Author,
+		"cover_url":         task.CoverURL,
+		"summary":           task.Summary,
+		"book_status":       task.BookStatus,
 		"status":            string(domain.TaskStatusPending),
 		"chapters_done":     0,
 		"chapters_total":    0,
 		"started":           time.Now().UTC().Format(time.RFC3339),
-		"initiator_user_id": initiatorUserID,
+		"initiator_user_id": task.InitiatorUserID,
+	}
+	if len(task.Genres) > 0 {
+		payload["genres"] = strings.Join(task.Genres, ",")
 	}
 	var rec struct {
 		ID string `json:"id"`
@@ -1176,6 +1184,12 @@ func parseImportTask(raw json.RawMessage) (domain.ImportTask, error) {
 		Title           string `json:"title"`
 		FileName        string `json:"file_name"`
 		FileType        string `json:"file_type"`
+		ObjectKey       string `json:"object_key"`
+		Author          string `json:"author"`
+		CoverURL        string `json:"cover_url"`
+		Genres          string `json:"genres"` // stored as comma-separated
+		Summary         string `json:"summary"`
+		BookStatus      string `json:"book_status"`
 		WorkerID        string `json:"worker_id"`
 		InitiatorUserID string `json:"initiator_user_id"`
 		Status          string `json:"status"`
@@ -1190,12 +1204,26 @@ func parseImportTask(raw json.RawMessage) (domain.ImportTask, error) {
 	}
 	started, _ := time.Parse(time.RFC3339, rec.Started)
 	finished, _ := time.Parse(time.RFC3339, rec.Finished)
+	var genres []string
+	if rec.Genres != "" {
+		for _, g := range strings.Split(rec.Genres, ",") {
+			if g = strings.TrimSpace(g); g != "" {
+				genres = append(genres, g)
+			}
+		}
+	}
 	return domain.ImportTask{
 		ID:              rec.ID,
 		Slug:            rec.Slug,
 		Title:           rec.Title,
 		FileName:        rec.FileName,
 		FileType:        rec.FileType,
+		ObjectKey:       rec.ObjectKey,
+		Author:          rec.Author,
+		CoverURL:        rec.CoverURL,
+		Genres:          genres,
+		Summary:         rec.Summary,
+		BookStatus:      rec.BookStatus,
 		WorkerID:        rec.WorkerID,
 		InitiatorUserID: rec.InitiatorUserID,
 		Status:          domain.TaskStatus(rec.Status),