Route badge spawns through a thread-safe queue

[supermarsx]

Summary

• add a mutex-protected queue to Overlay for cross-thread badge spawn requests
• process queued spawn requests on the overlay thread each frame before updating badges
• update the keyboard hook callback to enqueue spawn requests instead of spawning badges directly

Testing

• cmake -S . -B build -G Ninja (terminated after hanging while fetching external dependencies)

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https://chatgpt.com/codex/tasks/task_e_69069064aa6083258716b95a5bd95310