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/duplicate.go

@@ -49,11 +49,11 @@ var (
 
 func init() {
 	duplicateCmd.Flags().StringVar(&duplicateOf, "of", "", "Canonical issue ID (required)")
-	_ = duplicateCmd.MarkFlagRequired("of")
+	_ = duplicateCmd.MarkFlagRequired("of") // Only fails if flag missing (caught in tests)
 	rootCmd.AddCommand(duplicateCmd)
 
 	supersedeCmd.Flags().StringVar(&supersededWith, "with", "", "Replacement issue ID (required)")
-	_ = supersedeCmd.MarkFlagRequired("with")
+	_ = supersedeCmd.MarkFlagRequired("with") // Only fails if flag missing (caught in tests)
 	rootCmd.AddCommand(supersedeCmd)
 }