Derive client domain types from the shared schema contracts

Add entity/response Zod schemas to @trek/shared (place, trip, assignment, day, budget, packing, reservation), each matched against the producing server service, and re-export them from client types.ts instead of the hand-written duplicates that had drifted (name/title, amount/total_price, owner_id/user_id, cover_url/cover_image, ...). Updates the call sites and test fixtures the corrected types surfaced; type-only, no runtime behaviour change.

client/src/pages/PhotosPage.test.tsx

@@ -25,10 +25,10 @@ function buildPhoto(overrides: Partial<Photo> = {}): Photo {
   return {
     id: 1,
     trip_id: 1,
-    filename: 'photo1.jpg',
+    url: '/uploads/photos/photo1.jpg',
     original_name: 'photo1.jpg',
     mime_type: 'image/jpeg',
-    size: 12345,
+    file_size: 12345,
     caption: null,
     place_id: null,
     day_id: null,