fix(docker): single container (caddy+node), ESM adapters fix blank page

Docker: moved all docker files to docker/ tree (was conflated with
upstream Dockerfile at root + server/Dockerfile). Single container now:
caddy (front, serves static + proxies /api /ws) + node backend (internal
:4001). Node never exposed. entrypoint.sh runs both. Compose: one service.

Blank page root cause: storage adapters had inconsistent module systems.
firebase.js = ESM (export). ws.js + memory.js = CJS (module.exports).
CRA prod build = ESM strict -> CJS runtime crash, blank root. Dev mode
lenient, masked bug. First ws prod build (docker) = first exposure.
Never dev/prod split intended; just inconsistency from M2 era.

Fix: all adapters ESM. ws.js lazy-loads 'ws' pkg via dynamic import()
(Node/jest only; browser uses global WebSocket). index.js static
imports. server jest: added babel.config.js (preset-env, node target)
to transform ESM for jest.

Test: src/tests/StorageEsm.test.js — 4 tests grep all adapters for
module.exports / require(). Regression guard catches CJS leak.

Verified: docker page renders (root 4534 chars, UI visible).
server 24 green, shared 90 green, FE ESM 4 green.

server/Dockerfile

@@ -1,23 +0,0 @@
-# server/Dockerfile — backend (Express + ws + better-sqlite3)
-FROM node:18-alpine AS build
-WORKDIR /app
-
-# workspaces root needed: shared/ is a dependency (@ttrpg/shared)
-COPY package*.json ./
-COPY shared/package.json ./shared/
-COPY server/package.json ./server/
-RUN npm install --workspaces --include-workspace-root
-
-COPY shared/ ./shared/
-COPY server/ ./server/
-
-# better-sqlite3 builds native; rebuild for alpine musl
-RUN cd server && npm rebuild better-sqlite3
-
-ENV NODE_ENV=production
-ENV PORT=4001
-ENV DB_PATH=/data/tracker.sqlite
-
-EXPOSE 4001
-WORKDIR /app/server
-CMD ["node", "index.js"]

server/babel.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+  presets: [['@babel/preset-env', { targets: { node: 'current' } }]],
+};