fix(lint): resolve all errcheck violations in ingestion module

ingestion/internal/wiki/inventory.go

@@ -47,7 +47,7 @@ func readFrontmatter(path, fallbackSlug string) (title string, aliases []string)
 	if err != nil {
 		return
 	}
-	defer f.Close()
+	defer f.Close() //nolint:errcheck
 
 	scanner := bufio.NewScanner(f)
 	inFM := false

ingestion/internal/wiki/log.go

@@ -32,9 +32,9 @@ func AppendLog(brainDir, source string, pages, warnings []string, date string) e
 	if err != nil {
 		return fmt.Errorf("open log: %w", err)
 	}
-	defer f.Close()
 	if _, err = f.WriteString(sb.String()); err != nil {
+		f.Close() //nolint:errcheck
 		return fmt.Errorf("write log: %w", err)
 	}
-	return nil
+	return f.Close()
 }