Typed client creation

Identity

createApiClient and ApiError from @sapporta/shared/client; getApiBase from @sapporta/frontend/platform.

createApiClient(contract, options) returns a throwing client whose contract key becomes the method name.
Calls pass params, query, and body according to the route contract.
A QueryParamRecord value may contain a readonly string array. The client serializes that array as repeated URL keys in order, which preserves same-key table filters instead of collapsing them. Numeric table query inputs remain strings at this client boundary and are coerced by the shared contract on the server.
Use { baseUrl: getApiBase }, not { baseUrl: getApiBase() }. The client calls the resolver immediately before every request and prepends the result to the contract path.
validateResponse defaults to true. A response-schema mismatch rejects the call before response unwrapping.
A valid 2xx response returns its body. A non-2xx response that reaches unwrapping throws ApiError with numeric status and an unknown body.
Transport and response-validation failures pass through without fabricated HTTP statuses.
baseHeaders defaults to { "Content-Type": "application/json" }. credentials is passed to fetch; use the value required by the generated same-origin or split-origin authentication configuration.
Setting validateResponse: false disables client response-schema proof and should be an explicit compatibility decision, not routine feature setup.