Keep a push's unmade Supply run across week navigation

A push whose Supply run was not made was swept from the mutation cache as
soon as another week was shown. If the household pressed "Make the shopping
list" and moved to another week while it was being made, and making it then
failed, coming back showed neither the failure nor a way to make the list:
the week was left on Calendar with no shopping list (F17-R2).

keepWeekMutations now keeps a week's latest push whose Supply run was not
made whatever week is shown. It goes only when the list is made (settle), or
when a push, draft or swap of that week sends a new push or resets it; an
earlier push replaced by a later one is still swept as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/plan/PlanPage.test.tsx

@@ -577,6 +577,57 @@ describe('PlanPage', () => {
     expect(screen.queryByRole('button', { name: 'Make the shopping list' })).not.toBeInTheDocument()
   })
 
+  it('still says the Supply run could not be made when making the shopping list fails after leaving the week', async () => {
+    const made = deferred()
+    stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('draft')),
+      [`GET ${NEXT_WEEK}`]: () => errorResponse(404, 'not_found'),
+      [`POST ${PUSH}`]: () => jsonResponse(200, syncedNow(SUPPLY_RUN_FAILED)),
+      'POST /api/v1/shopping/2026-10-05/generate': () => made.response,
+    })
+    await renderPage()
+
+    fireEvent.click(await screen.findByRole('button', { name: 'Looks good — push to Calendar' }))
+    fireEvent.click(within(await screen.findByRole('alert')).getByRole('button', { name: 'Make the shopping list' }))
+    expect(await screen.findByRole('alert')).toHaveTextContent('Making the shopping list…')
+
+    // The week is left while the shopping list is being made, which fails.
+    fireEvent.click(screen.getByRole('button', { name: 'Next week' }))
+    expect(await screen.findByRole('button', { name: 'Draft this week' })).toBeInTheDocument()
+    await act(async () => made.send(errorResponse(500, 'internal')))
+
+    // Coming back, the Supply run is still said to be unmade, and can be
+    // made again.
+    fireEvent.click(screen.getByRole('button', { name: 'Previous week' }))
+    const alert = await screen.findByRole('alert')
+    expect(alert).toHaveTextContent("Pushed to Calendar, but this week's Supply run couldn't be made.")
+    expect(within(alert).getByRole('button', { name: 'Make the shopping list' })).toBeEnabled()
+  })
+
+  it('no longer says the Supply run could not be made once the shopping list is made after leaving the week', async () => {
+    const made = deferred()
+    stubServer({
+      [`GET ${THIS_WEEK}`]: () => jsonResponse(200, planBody('draft')),
+      [`GET ${NEXT_WEEK}`]: () => errorResponse(404, 'not_found'),
+      [`POST ${PUSH}`]: () => jsonResponse(200, syncedNow(SUPPLY_RUN_FAILED)),
+      'POST /api/v1/shopping/2026-10-05/generate': () => made.response,
+    })
+    await renderPage()
+
+    fireEvent.click(await screen.findByRole('button', { name: 'Looks good — push to Calendar' }))
+    fireEvent.click(within(await screen.findByRole('alert')).getByRole('button', { name: 'Make the shopping list' }))
+    expect(await screen.findByRole('alert')).toHaveTextContent('Making the shopping list…')
+
+    fireEvent.click(screen.getByRole('button', { name: 'Next week' }))
+    expect(await screen.findByRole('button', { name: 'Draft this week' })).toBeInTheDocument()
+    await act(async () => made.send(jsonResponse(200, { ...supplyRun(28), skipped: [] })))
+
+    fireEvent.click(screen.getByRole('button', { name: 'Previous week' }))
+    expect(await screen.findByText('Beef tacos')).toBeInTheDocument()
+    expect(screen.queryByRole('alert')).not.toBeInTheDocument()
+    expect(screen.queryByRole('button', { name: 'Make the shopping list' })).not.toBeInTheDocument()
+  })
+
   it('pushes nothing again until the changed plan is read and shown', async () => {
     let read: () => Response | Promise<Response> = () => jsonResponse(200, planBody('draft'))
     let push = () => errorResponse(409, 'plan_changed')