refactor(wallet-cli): Parameterise RpcHandler with struct-validated dispatch

[sirtimid]

Summary

Resolves #8777.

• Adds RpcHandler<TParams, TResult>, RpcHandlerDefinition<TParams, TResult> ({ paramsStruct, run }), and a defineHandler(paramsStruct, run) helper in daemon/types.ts. RpcHandlerMap now maps method names to definitions.
• rpc-socket-server.ts validates params against the handler's struct via superstruct.validate before dispatch and returns -32602 invalidParams on shape mismatch. Each handler body can now trust the shape of its argument.
• daemon-entry.ts:
  • getStatus uses literal(null).
  • call uses a defined struct that enforces a non-empty [string, ...Json[]] tuple, dropping the ad-hoc Array.isArray / typeof checks from the handler body.
  • Replaces the wallet.messenger.call as any cast with a single typed RpcDispatcher = messenger.call.bind(messenger) escape hatch.
• Adds @metamask/superstruct ^3.1.0 to wallet-cli (already used across the monorepo at this version).

Branched off rekm/wallet-cli; merge target intentionally kept on the feature branch rather than main. No changelog entry (folds into the package's existing 0.0.0 initial-release bullet).

Test plan

• yarn workspace @metamask/wallet-cli run test — 248 tests pass, 100% line/branch/function/statement coverage on the touched files.
• yarn lint:eslint packages/wallet-cli/src — clean.
• yarn constraints — clean.
• yarn workspace @metamask/wallet-cli run changelog:validate — clean.
• New server test covers the -32602 invalidParams path and verifies run is not invoked when the struct rejects.
• New struct tests on the call handler cover both the rejection cases (null, empty, non-string head, non-array) and the accepting case.

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