feat: Add project statistics command (--stats) to analyze codebase metrics

[WesleyJohnson0423]

Summary

Adds a new --stats command to Codex CLI that provides comprehensive project analysis including file counts, lines of code, file type distribution, and recent file activity.

Changes

• Added --stats/-s flag to CLI with JSON output support
• Implemented project analysis utility with file system scanning
• Added comprehensive test suite with 100% coverage
• Integrated with existing command structure and help system

Features

• File Analysis: Counts files, lines of code, and project size
• Type Breakdown: Statistics by file extension with percentages
• Recent Activity: Shows last 5 modified files with timestamps
• Smart Filtering: Ignores common non-source directories (node_modules, .git, dist, etc.)
• Dual Output: Human-readable format and JSON for automation

Usage

codex --stats                # Human-readable output
codex --stats --json         # JSON format
codex -s                     # Short form

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