feat(rank): add ViewerRankProgress owned entity + migration

One row per (viewer, format) tracking accumulated Point + MasterPoint.
Unique index on (ViewerId, Format) enforces one row per format per viewer
(mirrors owned-collection precedent per project_owned_collection_unique_index).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.Database/Migrations/20260704141307_AddViewerRankProgress.cs

@@ -0,0 +1,54 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace SVSim.Database.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddViewerRankProgress : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "ViewerRankProgress",
+                columns: table => new
+                {
+                    ViewerId = table.Column<long>(type: "bigint", nullable: false),
+                    Id = table.Column<int>(type: "integer", nullable: false)
+                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
+                    Format = table.Column<int>(type: "integer", nullable: false),
+                    Point = table.Column<int>(type: "integer", nullable: false),
+                    MasterPoint = table.Column<int>(type: "integer", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_ViewerRankProgress", x => new { x.ViewerId, x.Id });
+                    table.ForeignKey(
+                        name: "FK_ViewerRankProgress_Viewers_ViewerId",
+                        column: x => x.ViewerId,
+                        principalTable: "Viewers",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ViewerRankProgress_ViewerId_Format",
+                table: "ViewerRankProgress",
+                columns: new[] { "ViewerId", "Format" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_ViewerRankProgress_ViewerId_Format",
+                table: "ViewerRankProgress");
+
+            migrationBuilder.DropTable(
+                name: "ViewerRankProgress");
+        }
+    }
+}