Add F5/F9 save and load shortcuts and fix graphics timing at 60 FPS

[slmkhanahmed]

Summary

This pull request adds:

• F5 as a save shortcut
• F9 as a load shortcut
• A graphics fix for gameplay at 60 FPS

Changes

• Added handling for the F5 save key
• Added handling for the F9 load key
• Updated graphics-related timing or rendering behavior for 60 FPS

Testing

• Confirmed that F5 saves the game
• Confirmed that F9 loads the game
• Tested gameplay at 60 FPS
• Confirmed that existing save/load controls still work

Notes

I have reviewed the submitted code and understand how it works.

[slmkhanahmed]

The pull request is ready for review. GitHub shows “Cannot update this protected ref,” so a repository maintainer will need to review and merge it.

[SaturninTheAlien]

Thank you very much for your contribution to Pekka Kana 2!
Before I merge this PR for testing, could you please remove .runtime_test_data from the commit and add it to .gitignore?