Task 29's refactor added a package-private test-friendly constructor
alongside the public production one. Without @Autowired Spring cannot pick
which constructor to use for the @Component, and falls back to searching
for a no-arg default — crashing startup with 'No default constructor found'.
Detected when launching the server via the new docker-compose stack; unit
tests still pass because they invoke the package-private test constructor
directly.
5edf7eb23a