feat: Implement dynamic Gatekeeper proxy and enhance service health monitoring

- **Implemented Dynamic Gatekeeper (Anubis) Proxy:**
  - Introduced Anubis as a Gatekeeper proxy layer for services (`web`, `web-staging`, `feedback`, `health`).
  - Added `docker-gen` setup (`docker-compose_gatekeeper.template.yml`, `gatekeeper-manager`) to dynamically configure Anubis instances based on container labels (`enable_gatekeeper=true`).
  - Updated HAProxy to route traffic through the respective Gatekeeper services.

- **Enhanced Service Health Monitoring & Checks:**
  - Integrated `django-health-check` into the Django application, providing detailed health endpoints (e.g., `/health/`).
  - Replaced the custom health check view with `django-health-check` URLs.
  - Added `psutil` for system metrics in health checks.
  - Made Gatus configuration dynamic using `docker-gen` (`config.template.yaml`), allowing automatic discovery and monitoring of service instances (e.g., web workers).
  - Externalized Gatus SMTP credentials to environment variables.
  - Strengthened `docker-compose_core.yml` with a combined `db-redis-healthcheck` service reporting to Gatus.
  - Added explicit health checks for `db` and `redis` services in `docker-compose.yml`.

- **Improved Docker & Compose Configuration:**
  - Added `depends_on` conditions in `docker-compose.yml` for `web` and `celery` services to wait for the database.
  - Updated `ALLOWED_HOSTS` in `docker-compose_staging.yml` and `docker-compose_web.yml` to include internal container names for Gatekeeper communication.
  - Set `DEBUG=False` for staging services.
  - Removed `.env.production` from `.gitignore` (standardized to `.env`).
  - Streamlined `scripts/entrypoint.sh` by removing the call to the no-longer-present `/deploy.sh`.

- **Dependency Updates:**
  - Added `django-health-check>=3.18.3` and `psutil>=7.0.0` to `pyproject.toml` and `uv.lock`.
  - Updated `settings.py` to include `health_check` apps, configuration, and use `REDIS_URL` consistently.

- **Streamlined deployment script used in GHA:**
  - Updated the workflow to copy new server files and create a new `.env` file in the temporary directory before moving them into place.
  - Consolidated the stopping and removal of old containers into a single step for better clarity and efficiency.
  - Reduce container downtime by rearranging stop/start steps.

src/pkmntrade_club/django_project/settings.py

@@ -118,6 +118,15 @@ INSTALLED_APPS = [
     "crispy_tailwind",
     "tailwind",
     "django_linear_migrations",
+    'health_check',
+    'health_check.db',
+    'health_check.cache',
+    'health_check.storage',
+    'health_check.contrib.migrations',
+    'health_check.contrib.celery',
+    'health_check.contrib.celery_ping',
+    'health_check.contrib.psutil',
+    'health_check.contrib.redis',
     "meta",
 ] + FIRST_PARTY_APPS
 
@@ -155,6 +164,11 @@ if DEBUG:
         "django_browser_reload.middleware.BrowserReloadMiddleware",
     ]
 
+HEALTH_CHECK = {
+    'DISK_USAGE_MAX': 90,  # percent
+    'MEMORY_MIN': 100,    # in MB
+}
+
 DAISY_SETTINGS = {
     'SITE_TITLE': 'PKMN Trade Club Admin',
     'DONT_SUPPORT_ME': True,
@@ -208,7 +222,6 @@ AUTH_PASSWORD_VALIDATORS = [
     },
 ]
 
-
 # Internationalization
 # https://docs.djangoproject.com/en/dev/topics/i18n/
 # https://docs.djangoproject.com/en/dev/ref/settings/#language-code
@@ -344,6 +357,8 @@ CACHE_TIMEOUT = 604800 # 1 week
 
 DEBUG_TOOLBAR_CONFIG = {"SHOW_TOOLBAR_CALLBACK": lambda request: DEBUG}
 
+REDIS_URL = "redis://redis:6379"
+
 DISABLE_CACHE = env('DISABLE_CACHE', default=DEBUG)
 
 if DISABLE_CACHE:
@@ -356,12 +371,12 @@ else:
     CACHES = {
         "default": {
             "BACKEND": "django.core.cache.backends.redis.RedisCache",
-            "LOCATION": "redis://redis:6379",
+            "LOCATION": REDIS_URL,
         }
     }
 
-CELERY_BROKER_URL = "redis://redis:6379"
-CELERY_RESULT_BACKEND = "redis://redis:6379"
+CELERY_BROKER_URL = REDIS_URL
+CELERY_RESULT_BACKEND = REDIS_URL
 CELERY_TIMEZONE = "America/Los_Angeles"
 CELERY_ENABLE_UTC = True
 CELERY_BEAT_SCHEDULER = "django_celery_beat.schedulers:DatabaseScheduler"