Add Area of Effect (AOE) resource effects to grid objects

[daveey]

TL;DR

Added Area of Effect (AOE) resource effects to grid objects, allowing objects to emit resource effects to agents within a configurable range.

What changed?

• Added AOEEffectConfig class to configure resource effects with a range and resource deltas
• Extended GridObjectConfig with an optional AOE configuration
• Implemented AOEHelper class to manage AOE effects for grid objects
• Added CellEffect struct to track accumulated resource effects at each grid cell
• Modified Grid class to track and apply AOE effects across the grid
• Updated object initialization to support AOE effects in walls, chests, and assemblers
• Added Python bindings for the new AOE functionality
• Implemented proper cleanup of AOE effects when objects are removed

How to test?

1. Create a grid object with AOE effects:

from mettagrid.config import AOEEffectConfig, WallConfig

# Create a healing station that gives +1 health per tick
healing_station = WallConfig(
    map_name="healing_station",
    aoe=AOEEffectConfig(
        range=2,  # Manhattan distance of 2
        resource_deltas={"health": 1}  # +1 health per tick
    )
)

2. Place the object in your environment and observe agents within range receiving the configured resource effects each tick.

3. Test different ranges and resource combinations, including negative values for resource depletion effects.

Why make this change?

This feature enables more dynamic environments where grid objects can passively affect nearby agents. It supports a variety of gameplay mechanics such as:

• Healing stations that restore health to nearby agents
• Toxic areas that drain resources
• Resource generators that provide benefits to agents in proximity
• Environmental hazards with area effects
• Support for territory control mechanics where objects provide benefits to agents in controlled areas

This creates richer strategic gameplay where positioning relative to these effect-emitting objects becomes important.

[daveey]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Add observer_agent_id parameter to obs_features for agent-specific observations #4539
• Add Area of Effect (AOE) resource effects to grid objects #4538 👈 (View in Graphite)
• Add CommonsChest for shared inventory access across agents #4537
• Add Commons system for shared inventories between grid objects #4536
• Rename cog_arena.py to cogsguard.py and remove unused imports #4477
• Enhance attack system with armor, weapons, and configurable loot #4313 : 1 other dependent PR (#4321 )
• Make Transfer action optional and add vibe-triggered attack #4315
• Implement bidirectional resource transfer system with vibe-based triggers #4314
• Replace number_of_vibes with explicit vibes list in change_vibe action config #4489
• Refactor inventory system into dedicated InventoryConfig class #4356 : 2 other dependent PRs (#4328 , #4355 )
• Add ignore_limits parameter to inventory updates for initial setup #4360
• Rename test_performance to run_performance in mettagrid to avoid running in pytest #4370
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.