Assert partner and member route params in finance handlers.

Same hono 4.13 param widening as the previous fix; tsc only reported
the first bad argument per call, so these two were hidden behind it.

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

backend/src/routes/eventFinance.ts

@@ -597,7 +597,7 @@ financeRouter.delete('/:id/partners/:partnerId', requireEventPermission('edit_ex
   const eventId = c.req.param('id')!;
   const closed = await assertOpen(c, eventId);
   if (closed) return closed;
-  const existing = await loadPartner(eventId, c.req.param('partnerId'));
+  const existing = await loadPartner(eventId, c.req.param('partnerId')!);
   if (!existing) return c.json({ error: 'Partner not found' }, 404);
   const fronted = await dbGet<any>(
     (db as any).select({ id: (eventExpenses as any).id }).from(eventExpenses).where(eq((eventExpenses as any).paidByPartnerId, existing.id))
@@ -922,7 +922,7 @@ financeRouter.put('/:id/members/:memberId', requireEventPermission('manage_team'
 
 financeRouter.delete('/:id/members/:memberId', requireEventPermission('manage_team'), async (c) => {
   const eventId = c.req.param('id')!;
-  const existing = await loadMember(eventId, c.req.param('memberId'));
+  const existing = await loadMember(eventId, c.req.param('memberId')!);
   if (!existing) return c.json({ error: 'Member not found' }, 404);
   const user = currentUser(c);
   const target = await loadUser(existing.userId);