fancynpcs: Optimize NPC lookup by id

[JuliGame]

📋 Description

Optimized getNpcById from O(N) to O(1).

✅ Checklist

• My code follows the project's coding style and guidelines
• I have tested my changes locally and they work as expected
• I have added necessary documentation (if applicable)
• I have linked related issues using Fixes #issue_number or Closes #issue_number
• I have rebased/merged with the latest main branch

🔍 Changes

Changed fancynpcs-v2\src\main\java\de\oliver\fancynpcs\NpcManagerImpl.java from

    @Override
    public Npc getNpcById(String id) {
        for (Npc npc : getAllNpcs()) {
            if (npc.getData().getId().equals(id)) {
                return npc;
            }
        }

        return null;
    }

to

    @Override
    public Npc getNpcById(String id) {
        return npcs.get(id);
    }

This is free as Map<String, Npc> npcs is already a map with the ID as key, this preserves the existing behavior avoiding the linear scan.

Performance before the change:

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🧪 How to Test

1. use getNpcById