feat(api): add extended pet profile fields — schema, migration, CRUD, Zod validation

Adds five new nullable columns to the pets table:
- coat_type (text)
- temperament_score (integer, range 1–5)
- temperament_flags (jsonb, string[])
- medical_alerts (jsonb, typed MedicalAlert[])
- preferred_cuts (jsonb, string[])

Also:
- Exports MedicalAlert interface and MedicalAlertSeverity type from schema
- Updates shared Pet type in packages/types
- Adds Zod validators for all fields (ranges, max lengths, enum)
- Adds 14 tests covering happy path and validation edge cases
- Fixes drizzle.config.ts schema path (was ./src/schema.ts, correct is ./src/db/schema.ts)

Refs: GRO-1176

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

apps/api/drizzle.config.ts

@@ -1,7 +1,7 @@
 import { defineConfig } from "drizzle-kit";
 
 export default defineConfig({
-  schema: "./src/schema.ts",
+  schema: "./src/db/schema.ts",
   out: "./migrations",
   dialect: "postgresql",
   dbCredentials: {