Replaces the previous :requires_redis skip with a real test double so
the suite stays self-contained — no external Redis service needed in
CI, but the call paths through RedisHealthCheck and FourOhFourTracker
still get exercised end-to-end.
- Towerops.Redix.Fake: GenServer that speaks PING / SADD / SCARD /
SISMEMBER / SMEMBERS / EXPIRE / DEL / FLUSHDB. start_link refuses
anything other than localhost:6379 so failure-path tests still fail
the way they did against real Redix.
- Application supervisor starts the fake under name Towerops.Redix in
test env (instead of the dummy Agent stub).
- RedisHealthCheck and FourOhFourTracker now route Redix calls through
Application.get_env(:towerops, :redix_module, Redix). Test config
points it at the fake.
- Drops the test_helper :requires_redis exclusion and the @moduletag
on the two test files; FourOhFourTrackerTest setup just resets the
fake between runs.
The Forgejo CI test gate has no Redis service, so FourOhFourTracker
and RedisHealthCheck tests fail with Redix.ConnectionError. They've
always been broken in CI but the failures got noticed now.
Mirrors the existing :requires_gdal pattern: probe localhost:6379 in
test_helper.exs and add :requires_redis to extra_excludes when nothing
answers. Locally (where direnv runs Redis) the tag isn't excluded so
the tests still run.
- Use pattern match assertion in towerops_native_test to satisfy type checker
- Clear ETS whitelist cache in brute_force_test setup to prevent cross-test leakage
