Implement Achievement System

[mihaid11]

Create a robust achievement system that tracks player progress across all game activities and provides meaningful rewards. Includes a detailed achievement menu with visual progress indicators and reward collection mechanics.

Achievement Categories

• Combat: Enemy kills, boss defeats, specific tactics
• Tower Defense: Waves survived, perfect rounds, specific tower uses
• Collection: Items gathered, sets completed
• Other categories will be added as the game development progresses

Example of an achievement:

{
  "achievements": {
    "combat": [
      {
        "id": "first_blood",
        "name": "First Blood",
        "description": "Defeat your first enemy",
        "category": "combat",
        "tier": "bronze",
        "hidden": false,
        "max_progress": 1,
        "current_progress": 0,
        "completed": false,
        "reward_collected": false,
        "rewards": {
          "items": [{"id": 1, "quantity": 5}],
          "currency": {"crystals": 50},
        }
      }
    ]
  }
}

Priority: Low