feat: add cosmos plugin

[anilcse]

Relates to:

NA

Risks

NA

Background

What does this PR do?

This PR adds a Cosmos plugin for Eliza, enabling agents to interact with any Cosmos SDK-based chains (e.g., Osmosis, Cosmos Hub, Akash).

What kind of change is this?

Features (non-breaking change which adds functionality)

Documentation changes needed?

My changes do not require a change to the project documentation.

Testing

Where should a reviewer start?

• Look over the plugin-cosmos folder structure, especially providers/wallet.ts, actions/transfer.ts, and any environment or index files.
• Check the integration tests in tests/wallet.test.ts.

Detailed testing steps

1. Install dependencies for the plugin-cosmos package:

   pnpm install