feat: handles manual transaction approval

[andrew-virtuals]

Note

High Risk
High risk because it changes authentication signing from message-signing to EIP-712 typed data and modifies the Privy/Alchemy transaction submission path to support manual approval and new user-operation signing, impacting wallet security and transaction execution flow.

Overview
Switches agent/provider authentication from signMessage to EIP-712 typed-data signatures via new core/agentAuth.ts and updates all auth clients/context to send issuedAt + typed data instead of a raw message.

Adds a manual approval gate (core/approvalGate.ts) and a new SSE wallet stream alongside chat; SseTransport.connect() and AcpAgent.start() now accept configurable SupportedStreams (defaulting to chat+wallet) and the wallet stream resolves pending approvals.

Updates PrivyAlchemyEvmProviderAdapter to detect server-side APPROVAL_REQUIRED responses, wait for approval events before continuing, and changes call submission to a prepare/sign-user-operation/send-prepared flow using a configured ALCHEMY_SIGNING_CONTRACT.

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There are 3 total unresolved issues (including 2 from previous reviews).

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