[Alerts] Customizable job alerts + Help capabilities showcase

Job alerts (هشدار شغلی): users save what they want — scope (shift/job/both), role, city, shift type, employment type, minimum pay — and get notified when an employer posts a match. New JobAlert model + AlertScope enum + DbContext (user-cascade, role set-null, IsActive index) + migration. /Me/Alerts page to create/pause/delete alerts; entry point added to the کارجو panel. NotificationService.NotifyNewShift/Job now unions preference matches with active-alert matches (deduped) so alert owners are notified on publish. Help page gains an 'امکانات همکادر' capability showcase grid (with a 'ساخت هشدار شغلی' CTA) so the page demonstrates what the app does.

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

src/JobsMedical.Web/Pages/Me/Alerts.cshtml.cs

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+using System.Security.Claims;
+using JobsMedical.Web.Data;
+using JobsMedical.Web.Models;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Microsoft.EntityFrameworkCore;
+
+namespace JobsMedical.Web.Pages.Me;
+
+/// <summary>Job alerts (هشدار شغلی) — saved searches that notify the user on a new matching listing.</summary>
+[Authorize]
+public class AlertsModel : PageModel
+{
+    private readonly AppDbContext _db;
+    public AlertsModel(AppDbContext db) => _db = db;
+
+    public List<Role> Roles { get; private set; } = new();
+    public List<City> Cities { get; private set; } = new();
+    public List<JobAlert> Alerts { get; private set; } = new();
+    [TempData] public string? Msg { get; set; }
+
+    [BindProperty] public string? Label { get; set; }
+    [BindProperty] public AlertScope Scope { get; set; } = AlertScope.Any;
+    [BindProperty] public int? RoleId { get; set; }
+    [BindProperty] public int? CityId { get; set; }
+    [BindProperty] public ShiftType? ShiftType { get; set; }
+    [BindProperty] public EmploymentType? EmploymentType { get; set; }
+    [BindProperty] public long? MinPay { get; set; }
+
+    private int Uid => int.Parse(User.FindFirstValue(ClaimTypes.NameIdentifier)!);
+
+    public async Task OnGetAsync() => await LoadAsync();
+
+    public async Task<IActionResult> OnPostCreateAsync()
+    {
+        if (await _db.JobAlerts.CountAsync(a => a.UserId == Uid) >= 20)
+        {
+            Msg = "حداکثر تعداد هشدار شغلی ساخته شده است.";
+            return RedirectToPage();
+        }
+        _db.JobAlerts.Add(new JobAlert
+        {
+            UserId = Uid,
+            Label = string.IsNullOrWhiteSpace(Label) ? null : Label.Trim(),
+            Scope = Scope,
+            RoleId = RoleId,
+            CityId = CityId,
+            ShiftType = Scope == AlertScope.Jobs ? null : ShiftType,
+            EmploymentType = Scope == AlertScope.Shifts ? null : EmploymentType,
+            MinPay = MinPay is > 0 ? MinPay : null,
+        });
+        await _db.SaveChangesAsync();
+        Msg = "هشدار شغلی ساخته شد. به‌محض ثبت آگهی متناسب، باخبر می‌شوی.";
+        return RedirectToPage();
+    }
+
+    public async Task<IActionResult> OnPostToggleAsync(int id)
+    {
+        var a = await _db.JobAlerts.FirstOrDefaultAsync(x => x.Id == id && x.UserId == Uid);
+        if (a is not null) { a.IsActive = !a.IsActive; await _db.SaveChangesAsync(); }
+        return RedirectToPage();
+    }
+
+    public async Task<IActionResult> OnPostDeleteAsync(int id)
+    {
+        var a = await _db.JobAlerts.FirstOrDefaultAsync(x => x.Id == id && x.UserId == Uid);
+        if (a is not null) { _db.JobAlerts.Remove(a); await _db.SaveChangesAsync(); }
+        return RedirectToPage();
+    }
+
+    private async Task LoadAsync()
+    {
+        Roles = await _db.Roles.Where(r => r.IsActive).OrderBy(r => r.SortOrder).ToListAsync();
+        Cities = await _db.Cities.Where(c => c.IsActive).OrderBy(c => c.Name).ToListAsync();
+        Alerts = await _db.JobAlerts.Include(a => a.Role).Include(a => a.City)
+            .Where(a => a.UserId == Uid).OrderByDescending(a => a.CreatedAt).ToListAsync();
+    }
+}