feat(config): wire /config/update + /config/update_challenge_config (closes family 4/4)

is_skip_gacha_effect, use_challenge_two_pick_premium_card, and
challenge_two_pick_sleeve_id all persist on ViewerInfo and round-trip
through /load/index.

The two challenge fields move from the global ChallengeConfig section to
ViewerInfo — they're viewer preferences, not server-wide policy. Premium
card defaults to 0; sleeve falls back to DefaultLoadoutConfig.SleeveId
(3000011) when unset. MatchContextBuilder's TK2 sleeve read switches to
the same viewer-scoped path.

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

SVSim.Database/Migrations/20260613152024_ConfigViewerOverrides.cs

@@ -0,0 +1,51 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace SVSim.Database.Migrations
+{
+    /// <inheritdoc />
+    public partial class ConfigViewerOverrides : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<long>(
+                name: "Info_ChallengeTwoPickSleeveId",
+                table: "Viewers",
+                type: "bigint",
+                nullable: false,
+                defaultValue: 0L);
+
+            migrationBuilder.AddColumn<bool>(
+                name: "Info_IsSkipGachaEffect",
+                table: "Viewers",
+                type: "boolean",
+                nullable: false,
+                defaultValue: false);
+
+            migrationBuilder.AddColumn<bool>(
+                name: "Info_UseChallengeTwoPickPremiumCard",
+                table: "Viewers",
+                type: "boolean",
+                nullable: false,
+                defaultValue: false);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "Info_ChallengeTwoPickSleeveId",
+                table: "Viewers");
+
+            migrationBuilder.DropColumn(
+                name: "Info_IsSkipGachaEffect",
+                table: "Viewers");
+
+            migrationBuilder.DropColumn(
+                name: "Info_UseChallengeTwoPickPremiumCard",
+                table: "Viewers");
+        }
+    }
+}

SVSim.Database/Migrations/SVSimDbContextModelSnapshot.cs

@@ -4336,6 +4336,9 @@ namespace SVSim.Database.Migrations
                             b1.Property<DateTime>("BirthDate")
                                 .HasColumnType("timestamp with time zone");
 
+                            b1.Property<long>("ChallengeTwoPickSleeveId")
+                                .HasColumnType("bigint");
+
                             b1.Property<string>("CountryCode")
                                 .IsRequired()
                                 .HasColumnType("text");
@@ -4352,6 +4355,9 @@ namespace SVSim.Database.Migrations
                             b1.Property<bool>("IsPrizePreferred")
                                 .HasColumnType("boolean");
 
+                            b1.Property<bool>("IsSkipGachaEffect")
+                                .HasColumnType("boolean");
+
                             b1.Property<int>("MaxFriends")
                                 .HasColumnType("integer");
 
@@ -4361,6 +4367,9 @@ namespace SVSim.Database.Migrations
                             b1.Property<int>("SelectedEmblemId")
                                 .HasColumnType("integer");
 
+                            b1.Property<bool>("UseChallengeTwoPickPremiumCard")
+                                .HasColumnType("boolean");
+
                             b1.HasKey("ViewerId");
 
                             b1.HasIndex("SelectedDegreeId");

SVSim.Database/Models/Config/ChallengeConfig.cs

@@ -3,9 +3,6 @@ namespace SVSim.Database.Models.Config;
 [ConfigSection("Challenge")]
 public class ChallengeConfig
 {
-    public bool UseTwoPickPremiumCard { get; set; }
-    public long TwoPickSleeveId { get; set; }
-
     // Wire-mirrored fields from format_info (ChallengeData.cs parser)
     public int LastCardPackSetId { get; set; }
     public string CardPoolName { get; set; } = "";

SVSim.Database/Models/ViewerInfo.cs

@@ -12,6 +12,9 @@ public class ViewerInfo
     public bool IsOfficialMarkDisplayed { get; set; }
     public bool IsFoilPreferred { get; set; }
     public bool IsPrizePreferred { get; set; }
+    public bool IsSkipGachaEffect { get; set; }
+    public bool UseChallengeTwoPickPremiumCard { get; set; }
+    public long ChallengeTwoPickSleeveId { get; set; }
 
     #region Navigation Properties