refactor(docker): Enhance settings.py and deployment

This commit significantly refactors the Docker setup and application
configuration for improved robustness and flexibility.

Key changes include:

- Centralized Environment Variables:
  - Default values for essential settings (database, email, cache, etc.)
    are now defined in `django_project/settings.py` using `environ.Env`.
    This provides sensible defaults and reduces reliance on `.env` files,
    especially during Docker image builds.
  - `docker-compose.yml` no longer defines environment variables directly
    for `web` and `worker` services, deferring to `.env` and settings defaults.

- Dockerfile & Entrypoint Improvements:
  - `DJANGO_SETTINGS_MODULE` is now exclusively set as an ENV in `Dockerfile`, instead of setting it in `entrypoint.sh`
  - `entrypoint.sh` now conditionally appends `--static-path-mount`
    only to the `granian` command, leveraging the upgraded Granian's
    (v2.3.0+) ability to serve static files directly. The `STATIC_ROOT` is
    dynamically fetched from Django settings.

- Dependency Updates:
  - Upgraded `granian` from 2.2.5 to 2.3.1.
  - Upgraded `click` from 8.2.0 to 8.2.1.
  - `uv.lock` reflects these and other minor transitive dependency updates.

- Configuration Adjustments in `settings.py`:
  - Add defaults for all env variables, and set to default local dev settings
  - Introduced a `SCHEME` environment variable (defaulting to 'http')
    used for `CSRF_TRUSTED_ORIGINS`, `META_SITE_PROTOCOL`,
    `ACCOUNT_DEFAULT_HTTP_PROTOCOL`, etc.
  - `TIME_ZONE` and various email settings (host, port, user, password, TLS)
    are now configurable via environment variables with defaults.
  - `CELERY_TIMEZONE` now defaults to the `TIME_ZONE` setting.
  - Removed the unused `SCW_SECRET_KEY` variable (previously used for
    EMAIL auth).

pyproject.toml

@@ -49,7 +49,7 @@ dependencies = [
     "django-tailwind-4[reload]==0.1.4",
     "django-widget-tweaks==1.5.0",
     "gevent==25.4.1",
-    "granian==2.2.5",
+    "granian==2.3.1",
     "gunicorn==23.0.0",
     "idna==3.4",
     "oauthlib==3.2.2",