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/Properties/launchSettings.json

@@ -13,7 +13,7 @@
       "commandName": "Project",
       "dotnetRunMessages": true,
       "launchBrowser": true,
-      "launchUrl": "hangfire",
+      "launchUrl": "",
       "applicationUrl": "http://localhost:5271",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"
@@ -23,7 +23,7 @@
       "commandName": "Project",
       "dotnetRunMessages": true,
       "launchBrowser": true,
-      "launchUrl": "hangfire",
+      "launchUrl": "",
       "applicationUrl": "https://localhost:7027;http://localhost:5271",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"
@@ -32,7 +32,7 @@
     "IIS Express": {
       "commandName": "IISExpress",
       "launchBrowser": true,
-      "launchUrl": "hangfire",
+      "launchUrl": "",
       "environmentVariables": {
         "ASPNETCORE_ENVIRONMENT": "Development"
       }