feat(assets): 更新 Logo 与图片资源，添加数据层服务模块

- 更新 logo.svg/logo-light.svg/logo-white.svg 品牌标识
- 新增 logo-calligraphy.svg 书法体 Logo 变体
- 新增新闻、二维码、微信业务等图片资源
- 删除旧版 JPEG 测试图片
- 新增 CMS 数据层服务模块 (admin-api, auth, cms, crypto, db)
- 新增 cases/cross-references/methodology/team 常量数据
- 新增 site-config 站点配置

src/lib/crypto.ts

@@ -0,0 +1,69 @@
+import crypto from 'crypto';
+
+const ALGORITHM = 'aes-256-gcm';
+const IV_LENGTH = 16;
+const AUTH_TAG_LENGTH = 16;
+const SALT = 'novalon-cms-crypto-salt';
+
+/**
+ * 从 JWT token 派生加密密钥
+ */
+function deriveKey(token: string): Buffer {
+  return crypto.pbkdf2Sync(token, SALT, 10000, 32, 'sha256');
+}
+
+/**
+ * 加密数据
+ */
+export function encrypt(data: unknown, token: string): string {
+  const key = deriveKey(token);
+  const iv = crypto.randomBytes(IV_LENGTH);
+  const cipher = crypto.createCipheriv(ALGORITHM, key, iv);
+  
+  const json = JSON.stringify(data);
+  const encrypted = Buffer.concat([
+    cipher.update(json, 'utf8'),
+    cipher.final(),
+  ]);
+  const authTag = cipher.getAuthTag();
+
+  // 格式: iv + authTag + encrypted (全部 base64)
+  const combined = Buffer.concat([iv, authTag, encrypted]);
+  return combined.toString('base64');
+}
+
+/**
+ * 解密数据
+ */
+export function decrypt<T = unknown>(encryptedData: string, token: string): T {
+  const key = deriveKey(token);
+  const combined = Buffer.from(encryptedData, 'base64');
+
+  const iv = combined.subarray(0, IV_LENGTH);
+  const authTag = combined.subarray(IV_LENGTH, IV_LENGTH + AUTH_TAG_LENGTH);
+  const encrypted = combined.subarray(IV_LENGTH + AUTH_TAG_LENGTH);
+
+  const decipher = crypto.createDecipheriv(ALGORITHM, key, iv);
+  decipher.setAuthTag(authTag);
+
+  const decrypted = Buffer.concat([
+    decipher.update(encrypted),
+    decipher.final(),
+  ]);
+
+  return JSON.parse(decrypted.toString('utf8')) as T;
+}
+
+/**
+ * 生成随机 Token（用于前端存储的加密密钥）
+ */
+export function generateCryptoToken(): string {
+  return crypto.randomBytes(32).toString('hex');
+}
+
+/**
+ * 对敏感字段进行哈希（用于日志脱敏）
+ */
+export function hashSensitive(data: string): string {
+  return crypto.createHash('sha256').update(data + SALT).digest('hex').slice(0, 16);
+}