Implement core wallet connection and RPC calls

[rob1997]

What

Implement abstracted wallet connection and RPC calls to an RPC endpoint. This provides the foundation for all on-chain interactions, built on top of ChainSafe's web3.unity stack per the Open Creator Rails proposal.

Why

Games need a simple, consistent way to connect wallets and make RPC calls. Abstracting these operations allows the rest of the SDK (relay, access checks, subscriptions) to work regardless of the underlying wallet/RPC implementation. WP6 (Subject & Wallet Linkage) and WP3 rely on this layer.

How

• Abstract wallet connection (connect, disconnect, account management)
• Provide RPC call abstraction for chain queries and transactions
• Integrate with web3.unity signing and RPC stack
• Support configurable RPC endpoint

Acceptance Criteria

• Wallet connection flow works in Unity Editor and builds
• RPC calls can be made with configurable endpoint
• Abstractions allow swapping wallet/RPC implementations
• Works on desktop platforms (Windows/Mac/Linux); mobile where compatible

Estimation

Dependencies

• Part of [EPIC] Unity SDK #1

[boorich]

OUT OF SCOPE
The proposal is an implementation task: build wallet connection and RPC call abstractions in the Unity SDK on top of the ChainSafe web3.unity stack. This is infrastructure work within the Unity SDK's implementor scope. The primitive (subscriber, asset) → isSubscriptionActive is not changed — this work provides the foundation for calling protocol functions, but does not define or modify what those functions record or guarantee.
Wallet connection (connect, disconnect, account management) and RPC abstractions are implementor concerns. The protocol does not specify which wallet library an SDK uses or how it manages connections. This is free variation space for the Unity team.