Fix help flags to show root help instead of list help

Previously, 'opal -h', 'opal --help', and 'opal help' would show the
list command help instead of the root command help. This was because
the argument preprocessing logic would rewrite these as 'opal list -h'
before Cobra could handle them.

Now we detect help flags/command before preprocessing and let Cobra
handle them naturally. This ensures:
- 'opal -h' and 'opal --help' show root help
- 'opal help' shows root help
- 'opal help <command>' shows command-specific help
- 'opal <command> -h' still shows command-specific help
- All existing flexible syntax continues to work

opal-task/cmd/root.go

@@ -48,6 +48,16 @@ It supports filtering, tags, priorities, projects, and recurring tasks.`,
 }
 
 func Execute() error {
+	// Check for help flags/command BEFORE preprocessing
+	// This allows Cobra to handle help naturally for the root command
+	if len(os.Args) > 1 {
+		firstArg := os.Args[1]
+		if firstArg == "-h" || firstArg == "--help" || firstArg == "help" {
+			// Let Cobra handle help - skip preprocessing
+			return rootCmd.Execute()
+		}
+	}
+
 	// Preprocess arguments BEFORE Cobra routing
 	if len(os.Args) > 1 {
 		parsed := preprocessArgs(os.Args[1:])