feat(cli): add cobra-based CLI with subcommands

Replace simple argument parsing with cobra to provide better CLI experience:

- Add 'execute' subcommand for running TypeScript files
- Add 'types' subcommand for printing TypeScript type declarations
- Add help text and error handling
- Update documentation with new usage examples

Add dependencies: github.com/spf13/cobra, github.com/spf13/pflag

README.md

@@ -48,6 +48,12 @@ The project is cleanly separated into three packages:
 go build ./cmd/poiesis
 ```
 
+## CLI Options
+
+- `[file]` - Path to TypeScript file to execute (optional)
+- `--print-types` - Print TypeScript type declarations for all registered functions
+- `--help` - Show help information
+
 ## Testing
 
 ```bash
@@ -58,8 +64,9 @@ golangci-lint run
 ## Usage
 
 ```bash
-poiesis <typescript-file>
-poiesis -print-types
+poiesis execute [file]      # Run TypeScript file
+poiesis types               # Print TypeScript type declarations
+poiesis --help              # Show help
 ```
 
 ## Function System