adds Winstrate Challenge mystery encounter

[ben-lear]

https://github.com/user-attachments/assets/1461a890-907a-40ab-b951-4be0e7004460

https://github.com/user-attachments/assets/cf6ac2f8-ea1d-4adb-9bd6-53727d02fb76

https://github.com/user-attachments/assets/81287de7-1cf3-46a4-8519-98a76912a774

[netlify[bot]]

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