build: fix container image

Follow-up to #13, in which we introduced a source tarball for a
PL-authored npm dep, which is yet to be published.

.dockerignore

@@ -11,3 +11,6 @@
 !backend/
 !app/
 !public/
+
+# allow a specific source tarball, introduced in GH#13.
+!penumbra-zone-ui-tailwind-0.1.0.tgz

Containerfile

@@ -2,15 +2,17 @@
 # Should match what's in flake.nix for development.
 ARG NODE_MAJOR_VERSION=20
 FROM docker.io/node:${NODE_MAJOR_VERSION}-alpine AS base
+RUN corepack enable pnpm
+
 # Install dependencies only when needed
 FROM base AS deps
 # Check https://github.com/nodejs/docker-node/tree/b4117f9333da4138b03a546ec926ef50a31506c3#nodealpine to understand why libc6-compat might be needed.
 RUN apk add --no-cache libc6-compat
 WORKDIR /app
 
 # Install dependencies
-COPY package.json pnpm-lock.yaml* ./
-RUN corepack enable pnpm && pnpm install --frozen-lockfile
+COPY package.json pnpm-lock.yaml* penumbra-zone-ui-tailwind-0.1.0.tgz ./
+RUN pnpm install --frozen-lockfile
 
 # Rebuild the source code only when needed
 FROM base AS builder