[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/Models/Enums.cs

@@ -76,6 +76,14 @@ public enum ListingKind
     Job = 1
 }
 
+/// <summary>Which listing types a job alert watches.</summary>
+public enum AlertScope
+{
+    Any = 0,      // هر دو (شیفت و استخدام)
+    Shifts = 1,   // فقط شیفت
+    Jobs = 2      // فقط استخدام
+}
+
 /// <summary>
 /// Gender. On a listing it's the requirement (Any = فرقی نمی‌کند); on a person it's their gender
 /// (Any = unspecified).

src/JobsMedical.Web/Models/JobAlert.cs

@@ -0,0 +1,37 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace JobsMedical.Web.Models;
+
+/// <summary>
+/// A saved job alert ("هشدار شغلی") — the user describes what they're after (kind, role, city,
+/// shift type, employment type, minimum pay). When an employer publishes a matching shift/job,
+/// the matching engine notifies the owner. A user can keep several alerts; each can be paused.
+/// </summary>
+public class JobAlert
+{
+    public int Id { get; set; }
+
+    public int UserId { get; set; }
+    public User User { get; set; } = null!;
+
+    [MaxLength(120)] public string? Label { get; set; }      // optional friendly name
+
+    public AlertScope Scope { get; set; } = AlertScope.Any;
+
+    public int? RoleId { get; set; }                         // null = any role
+    public Role? Role { get; set; }
+
+    public int? CityId { get; set; }                         // null = any city
+    public City? City { get; set; }
+
+    public int? DistrictId { get; set; }                     // null = any district
+
+    public ShiftType? ShiftType { get; set; }                // for shifts; null = any
+    public EmploymentType? EmploymentType { get; set; }      // for jobs; null = any
+
+    /// <summary>Minimum acceptable pay (تومان): per-shift amount for shifts, monthly salary for jobs.</summary>
+    public long? MinPay { get; set; }
+
+    public bool IsActive { get; set; } = true;
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+}