Add slide puzzle game for issue #822 - #1248

✅ Developer Checklist

• I have followed all the guidelines mentioned in the README file.
• I have maintained the required directory structure. (Format: ProjectName/{USERNAME}/...yourfiles)
• This Pull Request contains only one project.
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Summary

Adds a picture sliding puzzle in SlidePuzzleGame/cobie1818/ for #822.

The game includes:

• A 3 × 3 picture puzzle with an original SVG landscape.
• Solvable shuffling through legal tile moves.
• A move counter and completion message.
• Mouse, touch, and keyboard controls.
• A responsive layout and reference picture.
• A README with setup instructions and manual test cases.

No external libraries or build step are required.

Testing

Manually checked:

• Tiles cannot move before starting.
• Shuffling resets the move counter.
• Adjacent tiles move and increase the counter.
• Invalid moves leave the board and counter unchanged.
• Enter and Space activate focused tiles.
• Restarting creates a new puzzle.
• The layout fits a 375-pixel viewport.

A controlled one-move board was used to check completion behavior.

Pre-commit checks:

• git diff --cached --check reported no whitespace errors.
• Reviewed the staged file list to confirm the five project files.
• Confirmed a clean working tree after committing and pushing.

Review

Feedback on the implementation, accessibility, and testing is welcome.

Screenshot