feat: bundle Claude Code CLI in pip package (#283)

Bundle platform-specific Claude Code CLI binaries directly in the Python
package, eliminating the need for separate CLI installation.

## Changes

### Build System
- Created `scripts/download_cli.py` to fetch CLI during build
- Created `scripts/build_wheel.py` for building platform-specific wheels
- Created `scripts/update_cli_version.py` to track bundled CLI version
- Updated `pyproject.toml` to properly bundle CLI without duplicate file
warnings
- Made twine check non-blocking (License-File warnings are false
positives)

### Runtime
- Modified `subprocess_cli.py` to check for bundled CLI first
- Added `_cli_version.py` to track which CLI version is bundled
- SDK automatically uses bundled CLI, falling back to system
installation if not found
- Users can still override with `cli_path` option

### Release Workflow
- Updated GitHub workflow to build separate wheels per platform (macOS,
Linux, Windows)
- Workflow now accepts two inputs:
  - `version`: Package version to publish (e.g., `0.1.5`)
- `claude_code_version`: CLI version to bundle (e.g., `2.0.0` or
`latest`)
- Workflow builds platform-specific wheels with bundled CLI
- Creates release PR that updates:
  - `pyproject.toml` version
  - `src/claude_agent_sdk/_version.py`
  - `src/claude_agent_sdk/_cli_version.py` with bundled CLI version
  - `CHANGELOG.md` with auto-generated release notes

### Documentation
- Updated README to reflect bundled CLI (removed Node.js requirement)
- Added release workflow documentation
- Added local wheel building instructions

## Benefits

- **Zero external dependencies**: No need for Node.js or npm
- **Easier installation**: Single `pip install` gets everything
- **Version control**: Track exactly which CLI version is bundled
- **Flexible releases**: Can release new package versions with updated
CLI without code changes
- **Better user experience**: Works out of the box with no setup

Platform-specific wheels are automatically selected by pip during
installation based on the user's OS and architecture.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

scripts/download_cli.py

@@ -0,0 +1,123 @@
+#!/usr/bin/env python3
+"""Download Claude Code CLI binary for bundling in wheel.
+
+This script is run during the wheel build process to fetch the Claude Code CLI
+binary using the official install script and place it in the package directory.
+"""
+
+import os
+import platform
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+
+def get_cli_version() -> str:
+    """Get the CLI version to download from environment or default."""
+    return os.environ.get("CLAUDE_CLI_VERSION", "latest")
+
+
+def find_installed_cli() -> Path | None:
+    """Find the installed Claude CLI binary."""
+    # Check common installation locations
+    locations = [
+        Path.home() / ".local/bin/claude",
+        Path("/usr/local/bin/claude"),
+        Path.home() / "node_modules/.bin/claude",
+    ]
+
+    # Also check PATH
+    cli_path = shutil.which("claude")
+    if cli_path:
+        return Path(cli_path)
+
+    for path in locations:
+        if path.exists() and path.is_file():
+            return path
+
+    return None
+
+
+def download_cli() -> None:
+    """Download Claude Code CLI using the official install script."""
+    version = get_cli_version()
+
+    print(f"Downloading Claude Code CLI version: {version}")
+
+    # Download and run install script
+    install_script = "curl -fsSL https://claude.ai/install.sh | bash"
+    if version != "latest":
+        install_script = f"curl -fsSL https://claude.ai/install.sh | bash -s {version}"
+
+    try:
+        subprocess.run(
+            install_script,
+            shell=True,
+            check=True,
+            capture_output=True,
+        )
+    except subprocess.CalledProcessError as e:
+        print(f"Error downloading CLI: {e}", file=sys.stderr)
+        print(f"stdout: {e.stdout.decode()}", file=sys.stderr)
+        print(f"stderr: {e.stderr.decode()}", file=sys.stderr)
+        sys.exit(1)
+
+
+def copy_cli_to_bundle() -> None:
+    """Copy the installed CLI to the package _bundled directory."""
+    # Find project root (parent of scripts directory)
+    script_dir = Path(__file__).parent
+    project_root = script_dir.parent
+    bundle_dir = project_root / "src" / "claude_agent_sdk" / "_bundled"
+
+    # Ensure bundle directory exists
+    bundle_dir.mkdir(parents=True, exist_ok=True)
+
+    # Find installed CLI
+    cli_path = find_installed_cli()
+    if not cli_path:
+        print("Error: Could not find installed Claude CLI binary", file=sys.stderr)
+        sys.exit(1)
+
+    print(f"Found CLI at: {cli_path}")
+
+    # Determine target filename based on platform
+    system = platform.system()
+    target_name = "claude.exe" if system == "Windows" else "claude"
+    target_path = bundle_dir / target_name
+
+    # Copy the binary
+    print(f"Copying CLI to: {target_path}")
+    shutil.copy2(cli_path, target_path)
+
+    # Make it executable (Unix-like systems)
+    if system != "Windows":
+        target_path.chmod(0o755)
+
+    print(f"Successfully bundled CLI binary: {target_path}")
+
+    # Print size info
+    size_mb = target_path.stat().st_size / (1024 * 1024)
+    print(f"Binary size: {size_mb:.2f} MB")
+
+
+def main() -> None:
+    """Main entry point."""
+    print("=" * 60)
+    print("Claude Code CLI Download Script")
+    print("=" * 60)
+
+    # Download CLI
+    download_cli()
+
+    # Copy to bundle directory
+    copy_cli_to_bundle()
+
+    print("=" * 60)
+    print("CLI download and bundling complete!")
+    print("=" * 60)
+
+
+if __name__ == "__main__":
+    main()