docs(UAT_PLAYBOOK): add TC-API-3.28 for pet_size_category enum verification (GRO-1999)

The 0037 migration (merged via PR #124 / GRO-1979) adds 'extra_large'
to the pet_size_category enum, fixing the 22P02 error in the UAT
seed-test-data job. Mirror the regression test added for coat_type
in TC-API-3.27: TC-API-3.28 explicitly verifies pet_size_category
contains all 4 values used by seed.ts  after
the seed job completes, so future enum drift on either dimension
surfaces at the UAT gate.

Refs: GRO-1999, GRO-1971 (precedent), PR #124 (the code fix).

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

packages/db/migrations/0037_add_extra_large_to_pet_size_category.sql

@@ -1,5 +1,5 @@
 -- Migration: 0037_add_extra_large_to_pet_size_category.sql
--- GRO-1999: Adds the 'extra_large' value to the pet_size_category enum.
+-- GRO-1979: Adds the 'extra_large' value to the pet_size_category enum.
 --
 -- 0031_buffer_rules.sql created pet_size_category with values
 -- ('small', 'medium', 'large', 'xlarge'), but seed.ts and the drizzle

packages/db/migrations/meta/_journal.json

@@ -262,4 +262,4 @@
       "breakpoints": true
     }
   ]
-}
+}