chore(docker): add development environment with hot reload

Add dev stage to Dockerfile and startup script
Create docker-compose.dev.yml for local development
Update README with Docker dev mode instructions

Dockerfile

@@ -12,6 +12,13 @@ FROM deps AS build
 COPY . .
 RUN pnpm build
 
+FROM deps AS dev
+ENV NODE_ENV=development
+COPY .docker/dev-start.sh /usr/local/bin/docker-dev-start
+RUN chmod +x /usr/local/bin/docker-dev-start
+EXPOSE 20013
+CMD ["docker-dev-start"]
+
 FROM base AS prod-deps
 COPY package.json pnpm-lock.yaml pnpm-workspace.yaml ./
 RUN pnpm install --frozen-lockfile --prod