[Feature]: Add Replay Mode for Step-by-Step Git Command Playback

[ErebAsh]

• closes [Feature]: Add Replay Mode to Git Playground #818

Summary

This PR introduces Replay Mode to the Git Playground — a powerful learning and debugging feature that allows users to rewind, replay, and analyze every Git command they execute, step by step. Replay Mode transforms the terminal into an interactive timeline, helping learners deeply understand how each command impacts repository state over time.

Changes Made

• Added a command recording system that captures deep state snapshots after every Git command
• Implemented Replay Mode toggle with restart, step navigation, and exit controls
• Created a visual command timeline panel with clickable steps and progress indicators
• Enforced a read-only terminal state during replay to prevent mutations
• Added keyboard shortcuts for fast replay navigation
• Displayed repository state details at each replay step
• Integrated replay cleanup with reset and scenario loading workflows

Keyboard Shortcuts

• ← / ↑ — Previous step
• → / ↓ — Next step
• Home — Restart replay
• End — Jump to final step
• Escape — Exit Replay Mode

Why This Matters

• Helps learners visually understand Git’s cause-and-effect
• Makes debugging mistakes significantly easier
• Encourages experimentation without fear
• Bridges the gap between commands and repository state
• Elevates the Git Playground into a professional-grade learning tool

Demo video

test107.mp4

Checklist

• Command-level state recording implemented
• Step-by-step replay navigation
• Timeline sidebar with direct step jumping
• Read-only replay protection
• Keyboard shortcut support
• Repository state visualization
• Seamless integration with scenarios & reset logic
• No breaking changes to existing workflows

This pull request is submitted as part of SWOC 2026.