refactor(cli): create cli package structure

Establish hatch/cli/ directory with package initialization as the
foundation for handler-based CLI architecture refactoring.

Deliverables:
- hatch/cli/__init__.py: Package init with main() export
- hatch/cli/__main__.py: Module entry point for python -m hatch.cli

Both files delegate to cli_hatch.main() for backward compatibility.
Full entry point migration planned for Task M1.7.

Author: LittleCoinCoin

hatch/cli/__init__.py

@@ -0,0 +1,21 @@
+"""CLI package for Hatch package manager.
+
+This package provides the command-line interface for Hatch, organized into
+domain-specific handler modules:
+
+- cli_utils: Shared utilities, exit codes, and helper functions
+- cli_mcp: MCP host configuration handlers
+- cli_env: Environment management handlers
+- cli_package: Package management handlers
+- cli_system: System commands (create, validate)
+
+The main entry point is the `main()` function which sets up argument parsing
+and routes commands to appropriate handlers.
+"""
+
+# Import main entry point from cli_hatch for now (will be moved in M1.7)
+from hatch.cli_hatch import main
+
+__all__ = [
+    'main',
+]

hatch/cli/__main__.py

@@ -0,0 +1,14 @@
+"""Entry point for running hatch.cli as a module.
+
+This allows running the CLI via: python -m hatch.cli
+
+Currently delegates to cli_hatch.main() for backward compatibility.
+Will be refactored in M1.7 to contain the full entry point logic.
+"""
+
+import sys
+
+from hatch.cli_hatch import main
+
+if __name__ == "__main__":
+    sys.exit(main())