chore: code health review - test fix and error comments (bd-9g1z, bd-ork0)

- Remove TestFindJSONLPathDefault from .test-skip (now passes)
- Add explanatory comments to 24 ignored error locations in cmd/bd:
  - Cobra flag methods (MarkHidden, MarkRequired, MarkDeprecated)
  - Best-effort cleanup/close operations
  - Process signaling operations

Part of code health review epic bd-tggf.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/show.go

@@ -1394,7 +1394,7 @@ func init() {
 	registerCommonIssueFlags(updateCmd)
 	updateCmd.Flags().String("notes", "", "Additional notes")
 	updateCmd.Flags().String("acceptance-criteria", "", "DEPRECATED: use --acceptance")
-	_ = updateCmd.Flags().MarkHidden("acceptance-criteria")
+	_ = updateCmd.Flags().MarkHidden("acceptance-criteria") // Only fails if flag missing (caught in tests)
 	updateCmd.Flags().IntP("estimate", "e", 0, "Time estimate in minutes (e.g., 60 for 1 hour)")
 	updateCmd.Flags().StringSlice("add-label", nil, "Add labels (repeatable)")
 	updateCmd.Flags().StringSlice("remove-label", nil, "Remove labels (repeatable)")