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.

uv.lock

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+version = "3.18.3"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "django" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/66/e9/0699ea3debfda75e5960ff99f56974136380e6f8202d453de7357e1f67fc/django_health_check-3.18.3.tar.gz", hash = "sha256:18b75daca4551c69a43f804f9e41e23f5f5fb9efd06cf6a313b3d5031bb87bd0", size = 20919 }
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+]
+
 [[package]]
 name = "django-linear-migrations"
 version = "2.17.0"
@@ -591,6 +603,7 @@ dependencies = [
     { name = "django-daisy" },
     { name = "django-debug-toolbar" },
     { name = "django-environ" },
+    { name = "django-health-check" },
     { name = "django-linear-migrations" },
     { name = "django-meta" },
     { name = "django-tailwind-4", extra = ["reload"] },
@@ -603,6 +616,7 @@ dependencies = [
     { name = "packaging" },
     { name = "pillow" },
     { name = "playwright" },
+    { name = "psutil" },
     { name = "psycopg" },
     { name = "psycopg-binary" },
     { name = "pycparser" },
@@ -635,6 +649,7 @@ requires-dist = [
     { name = "django-daisy", specifier = "==1.0.13" },
     { name = "django-debug-toolbar", specifier = "==4.4.6" },
     { name = "django-environ", specifier = "==0.12.0" },
+    { name = "django-health-check", specifier = ">=3.18.3" },
     { name = "django-linear-migrations", specifier = ">=2.17.0" },
     { name = "django-meta", specifier = "==2.4.2" },
     { name = "django-tailwind-4", extras = ["reload"], specifier = "==0.1.4" },
@@ -647,6 +662,7 @@ requires-dist = [
     { name = "packaging", specifier = "==23.1" },
     { name = "pillow", specifier = ">=11.2.1" },
     { name = "playwright", specifier = "==1.52.0" },
+    { name = "psutil", specifier = ">=7.0.0" },
     { name = "psycopg", specifier = "==3.2.3" },
     { name = "psycopg-binary", specifier = "==3.2.3" },
     { name = "pycparser", specifier = "==2.21" },
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 version = "3.2.3"