Refactor Health UI and enable static file support

- Added `app.UseStaticFiles()` to serve static files from `wwwroot`.
- Changed root path redirection to `/health-ui`.
- Moved inline CSS/JS from `Program.cs` to `health-ui.css` and `health-ui.js`.
- Updated navigation links in the health check HTML.
- Enhanced Health UI with improved styles and animations.
- Introduced countdown auto-refresh in `health-ui.js`.
- Updated `launchSettings.json` to start at the root URL.

ECMJobRunner.WebCron/wwwroot/js/health-ui.js

@@ -0,0 +1,15 @@
+let countdown = 10;
+
+function updateCountdown() {
+    document.getElementById('countdown').innerText = countdown;
+    countdown--;
+    if (countdown < 0) {
+        location.reload();
+    }
+}
+
+function autoRefresh() {
+    setInterval(updateCountdown, 1000);
+}
+
+window.onload = autoRefresh;