Fix price display issues and layout in design review page

- Add defensive checks in cart store to handle missing/NaN unitPrice values
- Display '—' for items with invalid prices instead of NaN
- Fix design review page grid layout to align buttons at top of page
- Ensure buttons don't get pushed below images on review page

.claude/settings.local.json

@@ -62,7 +62,8 @@
       "Bash(rm \"D:\\\\Craft2Prints\\\\src\\\\app\\\\admin\\\\designs\\\\[id]\\\\send-button.tsx\")",
       "Bash(git show *)",
       "Bash(git status *)",
-      "Bash(git revert *)"
+      "Bash(git revert *)",
+      "Bash(git commit -m 'Fix price display issues and layout in design review page *)"
     ]
   }
 }