refactor(client): the view DUs of the two order lanes, beside toDeferred

[halcwb]

Step 1 of plan #706 (#707), stacked on it: the view DUs of the two order lanes, next to today's toDeferred, read by nothing yet.

• OrderContextView = NoPatient | Evaluating | Settled | Changing, OrderPlanView = NoPatient | Opening | Settled of plan * selected | Changing of plan * selected; a selection without a plan cannot be written.
• OrderContextState.view and OrderPlanState.view project case for case as toDeferred does; the tests mirror the projection tests value for value.
• OrderPlanView.holds (the prescribe button's rule) and OrderContextView.dialog (the order dialog's context, settled or changing as the plan is) are the two page rules that are more than a match. dialog lives in the context machine file because it compiles after the plan's.
• A seed shows as Settled for now; that arm goes with Seeded in 646 step 4, after which this branch rebases.

Shared tests 513 green (6 new), Fable compile green, dependency rule green, 201 lines.

🤖 Generated with Claude Code

https://claude.ai/code/session_01K9K57bmde8G9rfreSMKZ6L

[greptile-apps]

Confidence Score: 5/5

This PR appears safe to merge.

What we checked:

• Machine file order: OrderPlanMachine.fs compiles first in both projects, and it does not refer back to OrderContextMachine. The new dependency is one-way and follows F# file order.
• View projection parity: Both view functions match the same state pairs and choose the same payloads as toDeferred. The added tests cover no patient, first load, settled data, and an active change.

Summary

The client now gives each order lane explicit page-ready view states instead of making pages interpret Deferred values. The new views keep the current screen visible during changes and add rules for the plan button and order dialog.

Diagram

sequenceDiagram
    participant U as Clinician
    participant P as Current page
    participant M as Order lane machine
    participant A as Server API
    participant T as Projection tests

    U->>P: Change an order or plan
    P->>M: Send command with request id
    M->>M: Keep held value and store request
    M->>A: Send command effect
    P->>M: Read toDeferred
    M-->>P: Provisional visible value
    T->>M: Read new view
    M-->>T: Changing visible value
    A-->>M: Return matching answer
    M->>M: Store answer and clear request
    P->>M: Read toDeferred
    M-->>P: Resolved held value
    T->>M: Read new view
    M-->>T: Settled held value

    alt No patient
        T->>M: Read new view
        M-->>T: NoPatient
    else First request has no held value
        T->>M: Read new view
        M-->>T: Evaluating or Opening
    end

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