Create new test for storage level over clustering year

[datejada]

Thanks, @abelsiqueira, it is looking good so far. I would like to use this change to add a test to this constraint. Maybe you can leverage Claude to get it done fast. The test is that it creates the constraints with a setup where we have:

• 4 seasonal storages:
  • 1 with inflows and initial storage level
  • 1 without inflows and initial storage level
  • 1 without inflows but with initial storage level
  • 1 with inflows and without initial storage level
• 1 non-seasonal storage
• 2 milestone years (e.g., 2030 and 2040)
• 2 representative periods per year
• You can have just a week (or a couple of days) in the timeframe to keep it small and simple (check the setup in the Storage Example for the RPs and the timeframe)

The idea is to check that the constraints are the right ones. I hope it is not much of a hassle. It is to cover this edge case that is not currently tested because changes like the ones in this PR will not show any error/problem.

Originally posted by @datejada in #1371 (review)

[datejada]

Close in favour of #1423