Add per-user Like (پسندیدن) with a liked page and counts

Logged-in users can like a listing (job/shift/talent); dislike is removed per request — only likes.
- Like model (polymorphic by TargetType+TargetId) + EF migration; unique per (user, listing).
- POST /like toggles the like (auth required) and returns {liked, count}.
- Detail pages: the old ♡ Save / ✕ Dismiss buttons are replaced by a single heart Like button that
  shows the live count and toggles in place; clicking while logged out redirects to login.
- New «❤️ پسندیده‌ها» page (/Me/Liked) lists everything the user liked (open listings only), with a
  nav entry shown only when authenticated.

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

src/JobsMedical.Web/Models/Enums.cs

@@ -119,6 +119,9 @@ public enum ContactType
     Other = 8       // سایر
 }
 
+/// <summary>What a <see cref="Like"/> points at.</summary>
+public enum LikeTargetType { Shift = 0, Job = 1, Talent = 2 }
+
 public enum ReportTargetType { Shift = 0, Job = 1, Facility = 2, User = 3 }
 public enum ReportStatus { Open = 0, Resolved = 1, Dismissed = 2 }
 

src/JobsMedical.Web/Models/Like.cs

@@ -0,0 +1,19 @@
+namespace JobsMedical.Web.Models;
+
+/// <summary>
+/// A logged-in user's «پسندیدن» of a listing (shift / job / talent). One row per (user, listing);
+/// toggling removes it. Polymorphic by <see cref="TargetType"/> + <see cref="TargetId"/> so one table
+/// covers all three listing kinds. The count of rows for a target is the public "likes" number.
+/// </summary>
+public class Like
+{
+    public int Id { get; set; }
+
+    public int UserId { get; set; }
+    public User User { get; set; } = null!;
+
+    public LikeTargetType TargetType { get; set; }
+    public int TargetId { get; set; }
+
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+}