feat(logistics): departure-after-arrival validation + travel/visa CSV export

- upsertFlightDetail throws BAD_REQUEST when departureAt < arrivalAt
- Travel tab: Download CSV button (project/attendee/email/flight fields/status/visa)
- Visas tab: Download CSV button (project/attendee/nationality/status/dates/notes)
- TDD: 2 new tests (rejects invalid, accepts valid); all 6 flight tests pass

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/logistics-flight.test.ts

@@ -174,6 +174,64 @@ describe('logistics flight detail procedures', () => {
     expect(count).toBe(1)
   })
 
+  it('upsertFlightDetail rejects when departureAt < arrivalAt', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const { program, lead, attendingMember } = await setupConfirmedFinalist(
+      `flight-dep-before-arr-${uid()}`,
+    )
+    programIds.push(program.id)
+    userIds.push(lead.id)
+
+    const caller = createCaller(logisticsRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+
+    const arrivalDate = new Date('2026-06-28T14:00:00Z')
+    const departureBeforeArrival = new Date('2026-06-28T10:00:00Z') // 4 hours earlier
+
+    await expect(
+      caller.upsertFlightDetail({
+        attendingMemberId: attendingMember.id,
+        arrivalAt: arrivalDate,
+        departureAt: departureBeforeArrival,
+        arrivalFlightNumber: 'AF7400',
+        departureFlightNumber: 'AF7405',
+      }),
+    ).rejects.toMatchObject({ code: 'BAD_REQUEST', message: 'Departure must be after arrival' })
+  })
+
+  it('upsertFlightDetail succeeds when departureAt >= arrivalAt', async () => {
+    const admin = await createTestUser('SUPER_ADMIN')
+    userIds.push(admin.id)
+    const { program, lead, attendingMember } = await setupConfirmedFinalist(
+      `flight-dep-after-arr-${uid()}`,
+    )
+    programIds.push(program.id)
+    userIds.push(lead.id)
+
+    const caller = createCaller(logisticsRouter, {
+      id: admin.id,
+      email: admin.email,
+      role: 'SUPER_ADMIN',
+    })
+
+    const arrivalDate = new Date('2026-06-28T10:00:00Z')
+    const departureAfterArrival = new Date('2026-06-30T14:00:00Z') // 2 days later
+
+    const result = await caller.upsertFlightDetail({
+      attendingMemberId: attendingMember.id,
+      arrivalAt: arrivalDate,
+      departureAt: departureAfterArrival,
+      arrivalFlightNumber: 'AF7400',
+      departureFlightNumber: 'AF7405',
+    })
+    expect(result.arrivalFlightNumber).toBe('AF7400')
+    expect(result.departureFlightNumber).toBe('AF7405')
+  })
+
   it('setFlightStatus toggles PENDING ↔ CONFIRMED', async () => {
     const admin = await createTestUser('SUPER_ADMIN')
     userIds.push(admin.id)