feat: node search picker, ByNode grouping fix, PDF export

- node picker: Search/Path on Repository, SearchNodes binding,
  debounced search dropdown showing title + full path
- ByNode summary groups by nodeID with NodePath as label (not NodeTitle)
- PDF export for worklog reports with embedded DejaVuSans fonts
- ExportWorklogPDF binding + button on Journal screen
- Removed unused Section field from ReportFilter
- ListReport now calls BuildReportPaths so nodePath is available
- go.sum: +github.com/signintech/gopdf dependency

internal/core/nodes/repository.go

@@ -185,6 +185,46 @@ func (r *Repository) CountChildren(parentID string, types ...string) (int, error
 	return count, err
 }
 
+// Search finds active nodes whose title contains the query (case-insensitive).
+func (r *Repository) Search(query string, limit int) ([]Node, error) {
+	q := `SELECT ` + nodeColumns + ` FROM nodes
+		WHERE deleted_at IS NULL AND title LIKE ? ORDER BY sort_order, title LIMIT ?`
+	rows, err := r.db.Query(q, "%"+query+"%", limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	return scanNodes(rows)
+}
+
+// Path builds the full path from root to the given node by walking parent_id chain.
+// Returns "title1 > title2 > ... > nodetitle". Returns empty string on error.
+func (r *Repository) Path(nodeID string) string {
+	var segments []string
+	currentID := nodeID
+	seen := make(map[string]bool)
+	for i := 0; i < 10; i++ {
+		if currentID == "" || seen[currentID] {
+			break
+		}
+		seen[currentID] = true
+		var title string
+		var parent sql.NullString
+		err := r.db.QueryRow(
+			`SELECT title, parent_id FROM nodes WHERE id = ?`, currentID,
+		).Scan(&title, &parent)
+		if err != nil {
+			break
+		}
+		segments = append([]string{title}, segments...)
+		if !parent.Valid {
+			break
+		}
+		currentID = parent.String
+	}
+	return strings.Join(segments, " > ")
+}
+
 // ListByParent returns children as *Node pointers. parentID must not be empty.
 func (r *Repository) ListByParent(parentID string) ([]*Node, error) {
 	rows, err := r.db.Query(