adding new ones for sudoku

[codewithharshit17]

#1363

📋 Description

This PR implements an interactive Sudoku Game complete with a real-time Recursive Backtracking Solver Visualizer. Instead of a standard terminal script, this implementation has been built directly into the web application frontend using the repository's native browser-terminal emulator structure. It allows users to play puzzles step-by-step or watch an AI programmatically solve constraint satisfaction problems live on the UI.

🚀 Proposed Changes

• Game Logic & UI (web-app/js/projects/sudoku-game.js): Created a fully responsive, vanilla JavaScript module that renders a formatted 9x9 grid inside the custom terminal dashboard.
• Play Mode: Added difficulty settings (Easy, Medium, Hard) that dynamically strip numbers from a pre-generated, valid seed board using randomized arrays. Supports step-by-step coordinate inputs.
• Auto-Solver Mode: Integrated a classic Depth-First Search (DFS) backtracking algorithm using async/await timeouts, giving a live, visual demonstration of the algorithm searching the decision tree.
• Registry Integration: Updated web-app/projects_registry.json and the root projects_registry.json to properly index the game in the sidebar and global search.

🛠️ Technical Details

• Zero External Dependencies: Built entirely using modern vanilla JavaScript and core web APIs.
• Constraint Satisfaction: Safe-placement utility functions automatically check and validate row, column, and 3x3 sub-grid rules.

---

📝 Checklist

• I am a registered GSSoC 2026 contributor.
• I have been explicitly assigned to this issue (💡 [Feature]: Add Interactive Sudoku Game with Recursive Backtracking Solver #1363) before opening this PR.
• My code follows the clean architecture and styling patterns of the existing web-app games.
• The game has been correctly registered in both registry JSON files.

@steam-bell-92 please review.

[vercel]

@codewithharshit17 is attempting to deploy a commit to the Anuj's projects Team on Vercel.

A member of the Team first needs to authorize it.