chore(output): remove FIXME

We don't use these accessors but it's fine to leave them

Author: cameronr

lua/opencode/ui/output.lua

@@ -191,7 +191,6 @@ end
 ---Get all lines as a table
 ---@return string[]
 function Output:get_lines()
-  -- FIXME: We probably don't need to use deepcopy here since Output is now short lived
   return vim.deepcopy(self.lines)
 end