feat: add health alerts field and delete actions for pets and clients (#25)

- Add health_alerts column to pets table (migration 0001)
- Update DB schema, shared types, and API Zod validation
- Show health alerts prominently (red badge) in pet cards
- Add health alerts field to pet form with allergy/condition placeholder
- Add delete button per pet with confirmation dialog
- Add delete client button with cascade warning

Closes groombook/groombook#2

Co-authored-by: Groom Book CTO <cto@groombook.app>
Co-authored-by: Paperclip <noreply@paperclip.ing>

packages/db/src/schema.ts

@@ -49,6 +49,7 @@ export const pets = pgTable("pets", {
   breed: text("breed"),
   weightKg: numeric("weight_kg", { precision: 5, scale: 2 }),
   dateOfBirth: timestamp("date_of_birth"),
+  healthAlerts: text("health_alerts"),
   groomingNotes: text("grooming_notes"),
   createdAt: timestamp("created_at").notNull().defaultNow(),
   updatedAt: timestamp("updated_at").notNull().defaultNow(),