refactor: PSK 签名改为 METHOD:path:timestamp 格式

- 签名内容不再包含 email，email 仅作审计
- 改用 METHOD:path:timestamp 防重放到不同端点
- X-Email 头改为可选
- medibot 签名: HMAC(PSK, 'POST:/api/v1/sites/x/submit:1234567890')

par-core/src/main/java/com/par/core/interceptor/HmacAuthInterceptor.java

@@ -62,10 +62,10 @@ public class HmacAuthInterceptor implements HandlerInterceptor {
         // 方式 2：PSK 签名
         String sig = request.getHeader(HEADER_SIGNATURE);
         String ts = request.getHeader(HEADER_TIMESTAMP);
-        String email = request.getHeader(HEADER_EMAIL);
-        if (sig != null && ts != null && email != null) {
+        if (sig != null && ts != null) {
             try {
-                if (pskService.verify(email, Long.parseLong(ts), sig) != null) {
+                if (pskService.verify(request.getMethod(), request.getRequestURI(),
+                        Long.parseLong(ts), sig) != null) {
                     request.setAttribute("accountId", 0L);
                     request.setAttribute("trustLevel", com.par.core.enums.TrustLevel.TRUSTED);
                     return true;

par-core/src/main/java/com/par/core/service/PskService.java

@@ -84,16 +84,15 @@ public class PskService {
 
     /**
      * 使用所有活跃 PSK 逐一验证签名
-     * signContent = email + ":" + timestamp
-     * @return 匹配的 PSK 版本号，null 表示验证失败
+     * signContent = METHOD:path:timestamp
+     * @return "ok" 表示验证通过，null 表示失败
      */
-    public String verify(String email, long timestamp, String signature) {
+    public String verify(String method, String path, long timestamp, String signature) {
         long now = System.currentTimeMillis() / 1000;
         if (Math.abs(now - timestamp) > 300) return null; // 5 分钟窗口
-        String payload = email.toLowerCase().trim() + ":" + timestamp;
+        String payload = method.toUpperCase() + ":" + path + ":" + timestamp;
 
-        String[] secrets = getActiveSecrets();
-        for (String secret : secrets) {
+        for (String secret : getActiveSecrets()) {
             if (HmacUtil.verify(secret, payload, signature)) {
                 return "ok";
             }