fix(mcp): create_order_context refuses a patient below the minimum

Is your feature request related to a problem? Please describe.

create_order_context in McpTools.GenOrder.fs takes every patient parameter as optional and builds the GenFORM patient from what was given, defaulting the department to ICK. A call without an age and without a weight and height gets a context with no rules and no scenarios, silently, where the web client is refused at the ingress since #646.

Describe the solution you'd like

The same rule at the MCP host: an age, or a measured weight and a height, else a refusal naming the minimum; and, until the server estimates (see the server-side estimation issue), a weight and a height, measured or estimated, else a refusal naming them. The same for get_order_scenarios and get_order_context_filter_options.

Additional context

Follow-up of plan 646 (docs/implementation-plans/646-patient-minimum.md, step 7); the web client's check is ServerApi.Ingress.fs.