feat(native): share a booking document to TREK and import it into a trip

TREK now appears under "Open in" and in the share sheet for PDFs, calendar
entries, Wallet passes and mails (iOS document types, Android VIEW and SEND
filters). The native side reads the file (up to 15 MB) and hands it to the UI,
which asks which trip it belongs to, upcoming trips first, then opens that
trip's booking import with the file already chosen.

client/src/native/sharedFiles.test.ts

@@ -0,0 +1,53 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { hasNativeFeature } from './capabilities';
+import { startSharedFiles, toFile, useSharedImportStore } from './sharedFiles';
+import { TrekShell } from './trekShell';
+
+vi.mock('./capabilities', () => ({ hasNativeFeature: vi.fn(), loadNativeCapabilities: vi.fn(async () => ({})) }));
+vi.mock('./trekShell', () => ({
+  TrekShell: { addListener: vi.fn(async () => ({ remove: async () => {} })), takeSharedFile: vi.fn() },
+  isUnimplemented: () => false,
+}));
+
+const PDF = { name: 'booking.pdf', mimeType: 'application/pdf', data: btoa('%PDF-1.4 hello') };
+
+beforeEach(() => {
+  useSharedImportStore.setState({ file: null, tripId: null });
+  vi.mocked(hasNativeFeature).mockReturnValue(true);
+  vi.mocked(TrekShell.takeSharedFile).mockReset().mockResolvedValue({ file: null });
+});
+
+describe('shared booking documents', () => {
+  it('turns the base64 the native side sends into a File', async () => {
+    const file = toFile(PDF);
+    expect(file.name).toBe('booking.pdf');
+    expect(file.type).toBe('application/pdf');
+    expect(await file.text()).toBe('%PDF-1.4 hello');
+  });
+
+  it('picks up a document shared before the UI ran, and the next ones as they come', async () => {
+    vi.mocked(TrekShell.takeSharedFile).mockResolvedValue({ file: PDF });
+    await startSharedFiles();
+    expect(useSharedImportStore.getState().file?.name).toBe('booking.pdf');
+
+    const listener = vi.mocked(TrekShell.addListener).mock.calls[0][1] as (p: typeof PDF) => void;
+    listener({ ...PDF, name: 'train.ics', mimeType: 'text/calendar' });
+    expect(useSharedImportStore.getState().file?.name).toBe('train.ics');
+  });
+
+  it('hands the file over once a trip is picked, and empties the queue', () => {
+    useSharedImportStore.getState().setFile(toFile(PDF));
+    useSharedImportStore.getState().chooseTrip(7);
+    expect(useSharedImportStore.getState().tripId).toBe(7);
+    expect(useSharedImportStore.getState().take()?.name).toBe('booking.pdf');
+    expect(useSharedImportStore.getState()).toMatchObject({ file: null, tripId: null });
+  });
+
+  it('does nothing in a binary without the feature', async () => {
+    vi.mocked(hasNativeFeature).mockReturnValue(false);
+    vi.mocked(TrekShell.addListener).mockClear();
+    await startSharedFiles();
+    expect(TrekShell.addListener).not.toHaveBeenCalled();
+    expect(TrekShell.takeSharedFile).not.toHaveBeenCalled();
+  });
+});