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/create.go

@@ -399,7 +399,7 @@ func init() {
 	registerCommonIssueFlags(createCmd)
 	createCmd.Flags().StringSliceP("labels", "l", []string{}, "Labels (comma-separated)")
 	createCmd.Flags().StringSlice("label", []string{}, "Alias for --labels")
-	_ = createCmd.Flags().MarkHidden("label")
+	_ = createCmd.Flags().MarkHidden("label") // Only fails if flag missing (caught in tests)
 	createCmd.Flags().String("id", "", "Explicit issue ID (e.g., 'bd-42' for partitioning)")
 	createCmd.Flags().String("parent", "", "Parent issue ID for hierarchical child (e.g., 'bd-a3f8e9')")
 	createCmd.Flags().StringSlice("deps", []string{}, "Dependencies in format 'type:id' or 'id' (e.g., 'discovered-from:bd-20,blocks:bd-15' or 'bd-20')")