Dungeon: Fix wrong item removal by using equals-based matching

[Shruti39]

Fixes #2698

This PR fixes a bug where InventoryComponent.removeOne removed the wrong
item when multiple items of the same class but different attributes
(e.g. health potions with different heal amounts) were present.

Changes:

• Updated removeOne(Item) to prefer exact instance matches and fall back
  to equals-based matching
• Overrode equals/hashCode in ItemPotionHealth to define semantic equality
  based on heal_amount

Other InventoryComponent methods already rely on equals(Item) and
therefore benefit automatically from the corrected equality semantics.
Class-based query methods were intentionally left unchanged.

[Flamtky]

This Javadoc now needs to be updated.

[AMatutat]

@Shruti39 can you give me an update?

If you resolved @Flamtky feedback, you have to re-request an new review, so he sees it.

[Shruti39]

@Shruti39 can you give me an update?

If you resolved @Flamtky feedback, you have to re-request an new review, so he sees it.

Set for start items no longer works when duplicate items (same class + attributes) are intended, e.g. multiple arrows.

I agree that start items should be represented as an ordered collection that allows duplicates (e.g. Item[] or List), since the amount is known upfront.

I can take this issue and prepare a PR that:

• replaces Set with Item[] (or List) for start items in CharacterClass
• updates the constructor and usages accordingly

Let me know if Item[] is preferred over List.

[Flamtky]

I agree that start items should be represented as an ordered collection that allows duplicates (e.g. Item[] or List), since the amount is known upfront.

I can take this issue and prepare a PR that:

• replaces Set with Item[] (or List) for start items in CharacterClass
• updates the constructor and usages accordingly

Let me know if Item[] is preferred over List.

We will use lists. I have already opened a PR for this change => #2779. This will allow us to focus on resolving issue #2698 in this PR.