test(db): add unit tests for test factories (GitHub #94)

Tests cover resetFactoryCounters(), counter determinism, override
merging, and compile-time enforcement of required fields on
buildAppointment. All 16 new tests pass (92 total).

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

pnpm-lock.yaml

@@ -51,7 +51,7 @@ importers:
         specifier: ^6.4.17
         version: 6.4.23
       '@vitest/coverage-v8':
-        specifier: ^3.0.4
+        specifier: ^3.2.4
         version: 3.2.4(vitest@3.2.4(@types/node@22.19.15)(jiti@2.6.1)(jsdom@26.1.0)(lightningcss@1.32.0)(terser@5.46.1)(tsx@4.21.0))
       eslint:
         specifier: ^9.18.0
@@ -66,7 +66,7 @@ importers:
         specifier: ^8.20.0
         version: 8.57.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)
       vitest:
-        specifier: ^3.0.4
+        specifier: ^3.2.4
         version: 3.2.4(@types/node@22.19.15)(jiti@2.6.1)(jsdom@26.1.0)(lightningcss@1.32.0)(terser@5.46.1)(tsx@4.21.0)
 
   apps/e2e:
@@ -166,6 +166,9 @@ importers:
       typescript:
         specifier: ^5.7.3
         version: 5.9.3
+      vitest:
+        specifier: ^3.0.4
+        version: 3.2.4(@types/node@22.19.15)(jiti@2.6.1)(jsdom@26.1.0)(lightningcss@1.32.0)(terser@5.46.1)(tsx@4.21.0)
 
   packages/types:
     devDependencies: