Find All Combinations of Bag Sizes That Sum to a Target Capacity

Given a list of chocolate bag sizes (each size may be used any number of times) and a target capacity n, find all unique combinations of bags whose sizes sum exactly to n. For example, given bag sizes [200, 100, 300] and target 500, return all combinations such as [200, 200, 100], [200, 300], [100, 100, 300], [100, 100, 100, 100, 100], etc. The core challenge is a backtracking/DFS search with deduplication to enumerate all valid combinations without permutation duplicates.