Add market object for resource trading

[daveey]

TL;DR

Added a new Market object that allows agents to buy and sell resources using hearts as currency.

What changed?

• Added Market and MarketConfig classes to implement a trading system
• Markets have terminals on different sides that can be configured for buying or selling
• Pricing is calculated dynamically based on inventory levels (100/sqrt(inventory))
• Added helper function opposite_direction() to determine which terminal an agent is using
• Updated agent inventory regeneration to support vibe-specific regeneration rates
• Added comprehensive tests for market functionality

How to test?

Run the new test file test_market.py which covers:

• Selling resources to the market
• Buying resources from the market
• Multiple trades in a single transaction
• Price changes based on inventory levels
• Edge cases like insufficient funds or out-of-stock items

You can also create a map with a market object and configure terminals on different sides to test buying and selling with different vibes.

Why make this change?

This adds an economic system to the game, allowing agents to trade resources and establish a currency-based economy. The market provides a way for agents to convert between different resource types at dynamically calculated prices, creating interesting economic dynamics and giving value to resource collection.

[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 market object for resource trading #4359 👈 (View in Graphite)
• Add AOE effects to grid objects #4328
• Refactor inventory system into dedicated InventoryConfig class #4356 : 2 other dependent PRs (#4355 , #4489 )
• 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

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[openhands-ai]

Looks like there are a few issues preventing this PR from being merged!

• GitHub Actions are failing:
  • Test and Benchmark

If you'd like me to help, just leave a comment, like

@OpenHands please fix the failing actions on PR #4359 at branch `daveey-market-2`

Feel free to include any additional details that might help me get this PR into a better state.

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