fix: add missing 'short'/'medium'/'silky' to coat_type enum (GRO-1971)

Migration 0031_buffer_rules.sql created coat_type enum with values
('smooth', 'double', 'wire', 'curly', 'long', 'hairless') but omitted
'short', 'medium', and 'silky' which are defined in schema.ts and
required by seed.ts.

Added 0035_add_missing_coat_type_values.sql to add the missing values
using ALTER TYPE ... ADD VALUE IF NOT EXISTS.

This resolves the UAT seed failure:
  PostgresError: invalid input value for enum coat_type: "short"
  code: '22P02' routine: 'enum_in' (packages/db/src/seed.ts)

Dev→UAT SDLC: QA (Lint Roller) review, then CTO review.

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

UAT_PLAYBOOK.md

@@ -114,6 +114,7 @@ GroomBook API is a Hono-based REST service (TypeScript/Node.js) powering the pet
 | TC-API-3.22 | Verify medicalAlerts shape | GET /api/pets/{id} for any pet with non-empty medicalAlerts | medicalAlerts is an array; each entry has type, description, severity |
 | TC-API-3.23 | Verify UAT test pet Charlie has behavioral alert | GET /api/pets/{id} where name = "TestCooper" (pet for uat-charlie@groombook.dev) | medicalAlerts includes an entry with type: "behavioral", severity: "low" or "high" |
 | TC-API-3.24 | Verify UAT test pet Delta has skin alert | GET /api/pets/{id} where name = "TestRocky" (pet for uat-delta@groombook.dev) | medicalAlerts includes an entry with type: "skin" |
+| TC-API-3.25 | Verify coat_type enum has all seed values | After UAT seed completes, inspect the coat_type enum on the UAT DB — it must contain: short, medium, long, double, wire, silky, curly, hairless | UAT seed jobs (`reset-demo-data`, `seed-test-data`) complete 1/1 with no `enum_in` error; coat_type includes all 8 values used by seed.ts `coatTypePool` |
 
 ### 4.4 Appointment Scheduling