fix: complete truncated ranking logic in set_rarity_ranks (closes #141)

[botbikamordehai2-sketch]

What

The set_rarity_ranks method in rarity_ranker.py was truncated, missing the rank assignment logic inside the loop and the return statement.

Fix

• When scores are equal (math.isclose), assign the same rank as the previous token
• Otherwise, use i + 1 as the rank
• Set token_rarity.rank = rank for each token
• Return sorted_token_rarities

Closes #141