feat: characterized the existing use cases as a baseline; every repo fake behaves like the real ones and can be told to fail, every use case is covered; gremlins runs clean on useCases

Taskfile.yml

@@ -57,7 +57,7 @@ tasks:
     desc: Gremlins mutation testing of the use cases → tmp/gremlins.json
     cmds:
       - mkdir -p tmp
-      - gremlins unleash --integration --tags nofrontend --output tmp/gremlins.json ./internal/infrastructure/useCases
+      - gremlins unleash --integration --tags nofrontend --coverpkg=./internal/infrastructure/useCases/... --timeout-coefficient 10 --output tmp/gremlins.json ./internal/infrastructure/useCases
 
   lint:
     desc: gofmt check, go vet, eslint (--fix) and vue-tsc