feat(site): integrate multilingual content management / 集成多语言内容管理

完善官网、管理后台与后端的多语言内容编辑和发布流程，调整站点页面及相关接口，并同步数据库脚本。

新增容器部署配置，改用环境变量注入数据库凭据；补充仓库忽略规则，并停止跟踪本地环境文件和 Maven 构建产物。

frontend/scripts/i18n-check.mjs

@@ -0,0 +1,81 @@
+import fs from 'node:fs/promises'
+import path from 'node:path'
+import process from 'node:process'
+import { fileURLToPath } from 'node:url'
+
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = path.dirname(__filename)
+
+function isPlainObject(v) {
+  return v != null && typeof v === 'object' && !Array.isArray(v)
+}
+
+function flattenKeys(obj, prefix = '') {
+  const out = new Set()
+  if (!isPlainObject(obj)) return out
+  for (const k of Object.keys(obj)) {
+    const next = prefix ? `${prefix}.${k}` : k
+    const v = obj[k]
+    if (isPlainObject(v)) {
+      for (const sub of flattenKeys(v, next)) out.add(sub)
+    } else {
+      out.add(next)
+    }
+  }
+  return out
+}
+
+function diff(a, b) {
+  // items in a but not in b
+  const out = []
+  for (const x of a) if (!b.has(x)) out.push(x)
+  out.sort()
+  return out
+}
+
+async function readJson(p) {
+  const raw = await fs.readFile(p, 'utf8')
+  return JSON.parse(raw)
+}
+
+async function main() {
+  const root = path.resolve(__dirname, '../src/locales')
+  const files = {
+    zh: path.join(root, 'zh.json'),
+    en: path.join(root, 'en.json'),
+    ja: path.join(root, 'ja.json')
+  }
+
+  const [zh, en, ja] = await Promise.all([readJson(files.zh), readJson(files.en), readJson(files.ja)])
+
+  const keysZh = flattenKeys(zh)
+  const keysEn = flattenKeys(en)
+  const keysJa = flattenKeys(ja)
+
+  const missingEn = diff(keysZh, keysEn)
+  const missingJa = diff(keysZh, keysJa)
+  const extraEn = diff(keysEn, keysZh)
+  const extraJa = diff(keysJa, keysZh)
+
+  const problems = []
+  if (missingEn.length) problems.push({ title: 'en 缺少 key', items: missingEn })
+  if (missingJa.length) problems.push({ title: 'ja 缺少 key', items: missingJa })
+  if (extraEn.length) problems.push({ title: 'en 多余 key', items: extraEn })
+  if (extraJa.length) problems.push({ title: 'ja 多余 key', items: extraJa })
+
+  if (problems.length) {
+    console.error('[i18n-check] locales key mismatch found:')
+    for (const p of problems) {
+      console.error(`\n- ${p.title}（${p.items.length}）`)
+      for (const it of p.items) console.error(`  - ${it}`)
+    }
+    process.exit(1)
+  }
+
+  console.log(`[i18n-check] OK: ${keysZh.size} keys in sync (zh/en/ja).`)
+}
+
+main().catch((err) => {
+  console.error('[i18n-check] Failed:', err)
+  process.exit(1)
+})