fix: disable fof/redis settings cache to avoid circular boot dependency (#7)

fof/redis >=1.1 introduces a `settings` service that replaces
SettingsRepositoryInterface with a Redis-backed caching layer.
Enabling it here creates a circular dependency: this extension reads
settings to decide which Redis services to enable, but with the
settings cache active those reads require Redis to already be wired.

Always disable the `settings` service when delegating to fof/redis.
Also fixes a cast-precedence bug in the database env var helpers
where `(int) getenv(...) ? getenv(...) : N` applied the cast to the
ternary condition rather than the result, causing REDIS_DATABASE_*=0
to return the default instead of 0.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

composer.json

@@ -20,7 +20,7 @@
   "require": {
     "php": "^8.1",
     "flarum/core": "^1.8.5",
-    "fof/redis": "^1.0"
+    "fof/redis": "^1.1.4"
   },
   "authors": [
     {