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/Migrations/20260623083624_Likes.cs

@@ -0,0 +1,56 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace JobsMedical.Web.Migrations
+{
+    /// <inheritdoc />
+    public partial class Likes : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "Likes",
+                columns: table => new
+                {
+                    Id = table.Column<int>(type: "integer", nullable: false)
+                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
+                    UserId = table.Column<int>(type: "integer", nullable: false),
+                    TargetType = table.Column<int>(type: "integer", nullable: false),
+                    TargetId = table.Column<int>(type: "integer", nullable: false),
+                    CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_Likes", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_Likes_Users_UserId",
+                        column: x => x.UserId,
+                        principalTable: "Users",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Likes_TargetType_TargetId",
+                table: "Likes",
+                columns: new[] { "TargetType", "TargetId" });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Likes_UserId_TargetType_TargetId",
+                table: "Likes",
+                columns: new[] { "UserId", "TargetType", "TargetId" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "Likes");
+        }
+    }
+}

src/JobsMedical.Web/Migrations/AppDbContextModelSnapshot.cs

@@ -727,6 +727,36 @@ namespace JobsMedical.Web.Migrations
                     b.ToTable("JobOpenings");
                 });
 
+            modelBuilder.Entity("JobsMedical.Web.Models.Like", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<int>("TargetId")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("TargetType")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("UserId")
+                        .HasColumnType("integer");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TargetType", "TargetId");
+
+                    b.HasIndex("UserId", "TargetType", "TargetId")
+                        .IsUnique();
+
+                    b.ToTable("Likes");
+                });
+
             modelBuilder.Entity("JobsMedical.Web.Models.Notification", b =>
                 {
                     b.Property<long>("Id")
@@ -1467,6 +1497,17 @@ namespace JobsMedical.Web.Migrations
                     b.Navigation("Role");
                 });
 
+            modelBuilder.Entity("JobsMedical.Web.Models.Like", b =>
+                {
+                    b.HasOne("JobsMedical.Web.Models.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
             modelBuilder.Entity("JobsMedical.Web.Models.Notification", b =>
                 {
                     b.HasOne("JobsMedical.Web.Models.User", "User")