Add --version command to CLI

[vitali87]

📋 Task Description

Implement a cgr --version command that displays the current package version.

🎯 Acceptance Criteria

• Running cgr --version or cgr -v shows the package version
• Version is read from pyproject.toml or package metadata (not hardcoded)
• Output format: code-graph-rag version X.Y.Z

🔗 Related Files/Components

• File: codebase_rag/cli.py
• File: pyproject.toml

📝 Additional Context

Typer supports version callbacks via typer.Option. Example:

from importlib.metadata import version

def version_callback(value: bool):
    if value:
        print(f"code-graph-rag version {version('code-graph-rag')}")
        raise typer.Exit()

🚦 Priority

• High
• Medium
• Low

📊 Estimated Effort

• Small (< 2 hours)
• Medium (2-8 hours)
• Large (> 8 hours)