Polish: live OFA age warning, puppy sorting, responsive fixes, form hints

- HealthRecordForm shows a live amber warning under Test Date when the dog is
  under the OFA minimum certification age (submit-time block unchanged)
- LitterDetail puppies sortable by name / sex / birth date
- Responsive at 375px: DogDetail photos+info grid stacks, header wraps;
  puppy grid uses min(220px,100%); navbar wraps with scrollable icon row;
  calendar uses minmax(0,1fr) columns so cells shrink instead of overflowing
- LitterForm explains why sire/dam selects are locked when editing
- Add .claude/launch.json for the vite dev server

Verified in-browser at 375px and desktop: no horizontal overflow on any page.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

client/src/App.css

@@ -139,14 +139,22 @@
     height: 4rem;
   }
   
-  .nav-links {
+  .navbar .container {
+    flex-wrap: wrap;
     gap: 0.25rem;
   }
-  
+
+  .nav-links {
+    gap: 0.25rem;
+    max-width: 100%;
+    overflow-x: auto;
+    -webkit-overflow-scrolling: touch;
+  }
+
   .nav-link span {
     display: none;
   }
-  
+
   .nav-link {
     padding: 0.625rem;
   }