feat(branding): add GroomBook logo and demo pet images for demo site

- Generated professional GroomBook logo using brand colors (sage green & warm brown)
- Created 4 realistic test pet images (Golden Retriever, Labrador, Poodle, Mixed Breed)
- Updated demo seed to reference pet image in demo database
- Assets are reloaded with demo data going forward

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/db/src/seed.ts

@@ -357,6 +357,7 @@ async function seedKnownUsers() {
       breed: "Golden Retriever",
       weightKg: "30.00",
       dateOfBirth: new Date("2020-06-15T00:00:00Z"),
+      image: "/demo-pets/dog-golden-retriever.png",
     });
     console.log("✓ Created pet 'Demo Dog'");
   }