Containerise: Dockerfile, Compose stack and wildcard TLS

One server now, the same image and env vars for many later: point
DJANGO_DATABASE_URL / DJANGO_REDIS_URL at central services, set a bucket, drop the
db and redis services, run several web containers behind a load balancer. No code
changes.

The wildcard certificate is what shapes this. Subdomain tenancy needs
*.rosterchief.app, and Let's Encrypt will not issue a wildcard over HTTP-01 -- only
DNS-01 -- so Caddy is built with a DNS provider plugin and needs an API token. That
single constraint is why the proxy is Caddy rather than the usual nginx+certbot.

The image apt-installs libpango and friends, which is what WeasyPrint binds to. The
PDF invoices that cannot render on a Mac without Homebrew work in the container by
construction.

Migrations are NOT run by the entrypoint: with more than one web container they
would race, and a starting gunicorn worker is a bad place to discover a failed
migration. Deploy runs them once, explicitly.

Two things the local build check caught, either of which would have failed the
image build at collectstatic (manifest storage treats a missing referenced file as
fatal):

- chart.js ended with a sourceMappingURL pointing at a .map we never vendored.
  Stripped, with an npm script so re-vendoring cannot bring it back.
- The Tailwind INPUT file lived at static/src/app.css, inside the served static
  tree, so collectstatic collected it and then choked on its @import "tailwindcss".
  It belongs outside: it is a build input, not an asset. Now assets/app.css.

Verified locally under gunicorn + WhiteNoise + manifest storage: pages serve and
the CSS comes back hashed. The image itself is unverified -- there is no container
runtime on this machine.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,73 @@
+# syntax=docker/dockerfile:1
+
+# --- 1. the stylesheet -------------------------------------------------------
+# Tailwind is a build-time concern: the CSS it emits is committed, but building it here means
+# the image never depends on someone having remembered to run `npm run build`.
+FROM node:22-slim AS css
+
+WORKDIR /build
+COPY package.json package-lock.json ./
+RUN npm ci
+COPY assets ./assets
+COPY templates ./templates
+COPY controlpanel ./controlpanel
+COPY billing ./billing
+RUN npm run build
+
+
+# --- 2. the runtime ----------------------------------------------------------
+FROM python:3.14-slim AS app
+
+# WeasyPrint binds to these at import: no pango, no invoices. This is also why building the
+# PDF path in a container is easier than on a Mac — apt has what Homebrew would have to.
+RUN apt-get update && apt-get install --no-install-recommends -y \
+        libpango-1.0-0 \
+        libpangoft2-1.0-0 \
+        libharfbuzz0b \
+        libffi8 \
+        libjpeg62-turbo \
+        libopenjp2-7 \
+        shared-mime-info \
+        curl \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
+
+ENV PYTHONUNBUFFERED=1 \
+    PYTHONDONTWRITEBYTECODE=1 \
+    UV_COMPILE_BYTECODE=1 \
+    UV_LINK_MODE=copy \
+    PATH="/app/.venv/bin:$PATH"
+
+WORKDIR /app
+
+# Dependencies first: they change far less often than the code, so this layer caches.
+COPY pyproject.toml uv.lock ./
+RUN --mount=type=cache,target=/root/.cache/uv \
+    uv sync --frozen --no-dev --no-install-project
+
+COPY . .
+COPY --from=css /build/static/css/app.css ./static/css/app.css
+
+RUN --mount=type=cache,target=/root/.cache/uv uv sync --frozen --no-dev
+
+# collectstatic needs a settings module that imports: a throwaway key, never used at runtime.
+RUN DJANGO_SECRET_KEY=build-only-not-a-secret \
+    DJANGO_STATICFILES_BACKEND=whitenoise.storage.CompressedManifestStaticFilesStorage \
+    python manage.py collectstatic --noinput
+
+RUN useradd --system --uid 1000 rosterchief && chown -R rosterchief /app
+USER rosterchief
+
+EXPOSE 8000
+
+# Migrations are NOT run here. With more than one app container they would race, and a failed
+# migration inside a starting web process is a bad place to find out — deploy runs them once,
+# explicitly (see DEPLOYMENT.md).
+CMD ["gunicorn", "rosterchief.wsgi:application", \
+     "--bind", "0.0.0.0:8000", \
+     "--workers", "3", \
+     "--threads", "4", \
+     "--timeout", "60", \
+     "--access-logfile", "-", \
+     "--error-logfile", "-"]