fix: 修復 /health 端點瀏覽器快取導致前端顯示過時更新時間

- 後端 /health 端點加入 Cache-Control no-cache 標頭
- 前端 fetch 呼叫加入 cache: 'no-store' 選項
- 修復 portal.html 無效的 timeout 選項

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/mes_dashboard/routes/health_routes.py

@@ -7,7 +7,7 @@ Provides /health endpoint for monitoring service status.
 from __future__ import annotations
 
 import logging
-from flask import Blueprint, jsonify
+from flask import Blueprint, jsonify, make_response
 
 from mes_dashboard.core.database import get_engine
 from mes_dashboard.core.redis_client import (
@@ -190,4 +190,9 @@ def health_check():
     if warnings:
         response['warnings'] = warnings
 
-    return jsonify(response), http_code
+    # Add no-cache headers to prevent browser caching
+    resp = make_response(jsonify(response), http_code)
+    resp.headers['Cache-Control'] = 'no-cache, no-store, must-revalidate'
+    resp.headers['Pragma'] = 'no-cache'
+    resp.headers['Expires'] = '0'
+    return resp

src/mes_dashboard/templates/portal.html

@@ -451,7 +451,7 @@
 
         async function checkHealth() {
             try {
-                const response = await fetch('/health', { timeout: 10000 });
+                const response = await fetch('/health', { cache: 'no-store' });
                 const data = await response.json();
 
                 // Update main indicator

src/mes_dashboard/templates/resource_status.html

@@ -1570,7 +1570,7 @@
 
     async function checkCacheStatus() {
         try {
-            const resp = await fetch('/health');
+            const resp = await fetch('/health', { cache: 'no-store' });
             const data = await resp.json();
 
             const dot = document.getElementById('cacheDot');