refactor: replace deprecated tbl_flatten with iter { ... }:flatten():totable()

[Bruenor]

This PR replaces usage of the deprecated tbl_flatten function with the recommended iter():flatten():totable() chain. This change ensures compatibility with the latest version of the library and avoids potential runtime warnings or future breakages.
🔧 Changes Made

• Replaced one instance of tbl_flatten(...) with iter(...):flatten():totable()
• Verified functional equivalence of the new implementation
  🧪 Testing
• Manually verified behavior in affected modules
  📌 Notes
• No additional dependencies introduced
• No breaking changes expected