fix CI lockfile sync and simplify Docker docs.

Regenerate package-lock for npm ci, bump Node to 22, and trim compose env to secrets only.

Co-authored-by: Cursor <cursoragent@cursor.com>

Dockerfile

@@ -1,19 +1,19 @@
 # syntax=docker/dockerfile:1
 
-FROM node:20-alpine AS deps
+FROM node:22-alpine AS deps
 WORKDIR /app
 COPY package.json package-lock.json* ./
 COPY prisma ./prisma
 RUN if [ -f package-lock.json ]; then npm ci; else npm install; fi
 
-FROM node:20-alpine AS build
+FROM node:22-alpine AS build
 WORKDIR /app
 COPY --from=deps /app/node_modules ./node_modules
 COPY . .
 ENV DATABASE_URL="file:./data/sejong.db"
 RUN mkdir -p data && npx prisma generate && npm run build
 
-FROM node:20-alpine AS runner
+FROM node:22-alpine AS runner
 WORKDIR /app
 ENV NODE_ENV=production
 ENV HOST=0.0.0.0