[Demo] Add admin demo-mode toggle + generic website ingest source

- AppSetting: DemoMode, WebsitesEnabled, WebsiteUrls
- Facility.IsDemo flag; SeedData split into SeedReferenceAsync (always)
  + SeedDemoAsync/ClearDemoAsync (idempotent, toggleable at runtime)
- WebsiteListingSource: scrape any admin-configured URL (og:title + content)
- Admin Settings: seed/clear demo card, demo-mode checkbox, website source
  fields; Program.cs seeds demo when DemoMode on (or in Development)
- EF migration DemoModeAndWebsites

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/JobsMedical.Web/Services/Scraping/SettingsService.cs

@@ -41,6 +41,9 @@ public class SettingsService
         s.TelegramChannels = incoming.TelegramChannels?.Trim();
         s.BaleEnabled = incoming.BaleEnabled;
         s.BaleBotToken = incoming.BaleBotToken?.Trim();
+        s.DemoMode = incoming.DemoMode;
+        s.WebsitesEnabled = incoming.WebsitesEnabled;
+        s.WebsiteUrls = incoming.WebsiteUrls?.Trim();
         s.DivarEnabled = incoming.DivarEnabled;
         s.DivarCity = string.IsNullOrWhiteSpace(incoming.DivarCity) ? "tehran" : incoming.DivarCity.Trim();
         s.DivarQueries = incoming.DivarQueries?.Trim();

src/JobsMedical.Web/Services/Scraping/WebsiteListingSource.cs

@@ -0,0 +1,69 @@
+using System.Net;
+using System.Text.RegularExpressions;
+using JobsMedical.Web.Models;
+
+namespace JobsMedical.Web.Services.Scraping;
+
+/// <summary>
+/// Generic website source: fetches each admin-configured URL and extracts readable text
+/// (JobPosting/Product JSON-LD description, common content containers, or og:title+description).
+/// Lets the admin point the engine at any job page / channel archive / classifieds listing.
+/// </summary>
+public class WebsiteListingSource : IListingSource
+{
+    private readonly IHttpClientFactory _http;
+    private readonly ILogger<WebsiteListingSource> _log;
+
+    public WebsiteListingSource(IHttpClientFactory http, ILogger<WebsiteListingSource> log)
+    {
+        _http = http;
+        _log = log;
+    }
+
+    public string Name => "وب‌سایت‌ها";
+
+    public async Task<IReadOnlyList<ScrapedItem>> FetchAsync(AppSetting s, CancellationToken ct = default)
+    {
+        var urls = AppSetting.SplitList(s.WebsiteUrls);
+        if (!s.WebsitesEnabled || urls.Count == 0) return Array.Empty<ScrapedItem>();
+
+        var client = _http.CreateClient("scrape");
+        var items = new List<ScrapedItem>();
+        foreach (var url in urls.Where(u => u.StartsWith("http")))
+        {
+            try
+            {
+                var html = await client.GetStringAsync(url, ct);
+                var text = Extract(html);
+                if (text.Length >= 25) items.Add(new ScrapedItem($"وب‌سایت ({Host(url)})", text, url));
+            }
+            catch (Exception ex) { _log.LogWarning(ex, "Website fetch failed for {Url}", url); }
+        }
+        return items;
+    }
+
+    private static string Host(string url) => Uri.TryCreate(url, UriKind.Absolute, out var u) ? u.Host : "web";
+
+    private static string Extract(string html)
+    {
+        string? title = Meta(html, "og:title");
+        if (title is not null) { var bar = title.IndexOf('|'); if (bar > 10) title = title[..bar].Trim(); }
+        string? body = Between(html, "rtcl-description") ?? Between(html, "entry-content")
+                    ?? Between(html, "job-description") ?? Meta(html, "og:description");
+        var text = HtmlUtil.ToPlainText(string.Join("\n", new[] { title, body }.Where(x => !string.IsNullOrWhiteSpace(x))));
+        return text.Length > 1800 ? text[..1800] : text;
+    }
+
+    private static string? Meta(string html, string prop)
+    {
+        var m = Regex.Match(html, $"<meta[^>]+property=[\"']{Regex.Escape(prop)}[\"'][^>]+content=[\"']([^\"']*)[\"']");
+        return m.Success ? WebUtility.HtmlDecode(m.Groups[1].Value) : null;
+    }
+
+    private static string? Between(string html, string cls)
+    {
+        var m = Regex.Match(html, $"<(?:div|article)[^>]+class=[\"'][^\"']*{Regex.Escape(cls)}[^\"']*[\"'][^>]*>(.*?)</(?:div|article)>",
+            RegexOptions.Singleline);
+        return m.Success ? m.Groups[1].Value : null;
+    }
+}