feat(leader-skin): shop catalog + 5 endpoints (/products, /buy, /buy_set, /buy_set_item, /ids)

Schema: LeaderSkinShopSeries -> Products (owned rewards) + owned
SetCompletionRewards on the series; ViewerLeaderSkinSetClaim composite
PK (ViewerId, SeriesId) backs the /buy_set_item idempotent-claim check.

Importer mirrors SleeveShopImporter: idempotent find-or-create, owned
collections rewritten wholesale on rerun. 16 series, 104 products.

Controller (extends existing /set with 5 new endpoints):
- /products: dict-keyed-by-series_id-string wire shape. is_completed
  per-viewer, rewards.status from ViewerLeaderSkinSetClaim (0=no set
  sale, 1=available, 2=claimed) matching client RewardStatus enum.
- /buy: single skin, sales_type 1/2 dispatch, 3=>501.
- /buy_set: whole series at SetPrice; requires set_sales_status != 0;
  grants every product's rewards (RewardGrantService idempotent on
  already-owned cosmetics, so partial-set buys don't double-add).
- /buy_set_item: requires viewer owns every skin in series; idempotent
  on re-claim (returns 200 + empty reward_list, not 400) so client
  retries don't error.
- /ids: flat owned-skin-id list for badge refresh.

496 tests pass (was 486; +10 leader-skin-shop tests).

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

SVSim.Database/Models/LeaderSkinShopProductEntry.cs

@@ -0,0 +1,36 @@
+using SVSim.Database.Common;
+
+namespace SVSim.Database.Models;
+
+/// <summary>
+/// One purchasable leader-skin product. PK = wire product_id (small ints in captures — e.g. 31,
+/// 165, 166). FK <see cref="SeriesId"/>. <see cref="LeaderSkinId"/> points at the
+/// <see cref="LeaderSkinEntry"/> the buyer ends up owning.
+/// </summary>
+public class LeaderSkinShopProductEntry : BaseEntity<int>
+{
+    public int SeriesId { get; set; }
+    public int LeaderSkinId { get; set; }
+
+    /// <summary>SystemText keys — resolved client-side via Data.Master.GetLeaderSkinProductText.</summary>
+    public string ProductNameKey { get; set; } = string.Empty;
+    public string IntroductionKey { get; set; } = string.Empty;
+    public string CvNameKey { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Per-product price for solo buy. Captures consistently show crystal/rupy parity for
+    /// regular skins (500c / 500r single, 400 unit-price when bought as set). Nullable so
+    /// promotions can offer one currency without the other.
+    /// </summary>
+    public int? SinglePriceCrystal { get; set; }
+    public int? SinglePriceRupy { get; set; }
+    public int? SinglePriceTicket { get; set; }
+    public int? TicketNumber { get; set; }
+    public long? TicketItemId { get; set; }
+
+    public bool IsEnabled { get; set; }
+
+    public List<LeaderSkinShopProductRewardEntry> Rewards { get; set; } = new();
+
+    public LeaderSkinShopSeriesEntry? Series { get; set; }
+}

SVSim.Database/Models/LeaderSkinShopProductRewardEntry.cs

@@ -0,0 +1,17 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace SVSim.Database.Models;
+
+/// <summary>
+/// One per-buy reward attached to a leader-skin product. Owned by
+/// <see cref="LeaderSkinShopProductEntry"/>. Captures show each skin product bundles 3 rewards:
+/// the skin itself (type=10), the matching emblem (type=7), and the matching sleeve (type=6).
+/// </summary>
+[Owned]
+public class LeaderSkinShopProductRewardEntry
+{
+    public int OrderIndex { get; set; }
+    public int RewardType { get; set; }   // Wizard.UserGoods.Type
+    public long RewardDetailId { get; set; }
+    public int RewardNumber { get; set; }
+}

SVSim.Database/Models/LeaderSkinShopSeriesEntry.cs

@@ -0,0 +1,33 @@
+using SVSim.Database.Common;
+
+namespace SVSim.Database.Models;
+
+/// <summary>
+/// One leader-skin-shop series (a themed collection — e.g. "7th Anniversary Skins").
+/// PK = wire series_id. <see cref="SetSalesStatus"/> controls whether the per-series
+/// "buy whole set" UI is offered: 0=none (single-skin purchases only), non-zero=set sale active.
+/// When set-active, the set-price + set-completion-reward fields are populated.
+/// </summary>
+public class LeaderSkinShopSeriesEntry : BaseEntity<int>
+{
+    public bool IsNew { get; set; }
+    public bool IsEnabled { get; set; }
+
+    /// <summary>SkinSeriesPurchaseInfo.eSetSalesStatus — 0=None.</summary>
+    public int SetSalesStatus { get; set; }
+
+    public int? SetPriceCrystal { get; set; }
+    public int? SetPriceRupy { get; set; }
+    public int? SetPriceTicket { get; set; }
+    public long? SetPriceTicketId { get; set; }
+
+    /// <summary>
+    /// SkinSeriesPurchaseInfo.RewardStatus — 0=none. The per-VIEWER claim state is computed
+    /// at request time from <see cref="ViewerLeaderSkinSetClaim"/>; this column is the catalog
+    /// default surfaced when no viewer is in context (or when set_sales_status==0).
+    /// </summary>
+    public int SetCompletionRewardStatus { get; set; }
+
+    public List<LeaderSkinShopProductEntry> Products { get; set; } = new();
+    public List<LeaderSkinShopSeriesRewardEntry> SetCompletionRewards { get; set; } = new();
+}

SVSim.Database/Models/LeaderSkinShopSeriesRewardEntry.cs

@@ -0,0 +1,18 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace SVSim.Database.Models;
+
+/// <summary>
+/// One set-completion bonus item attached to a leader-skin series. Owned by
+/// <see cref="LeaderSkinShopSeriesEntry"/>. Granted by /leader_skin/buy_set_item once the
+/// viewer owns every skin in the series. Wire shape: entries inside
+/// <c>rewards.items[]</c> on the per-series block of /leader_skin/products.
+/// </summary>
+[Owned]
+public class LeaderSkinShopSeriesRewardEntry
+{
+    public int OrderIndex { get; set; }
+    public int RewardType { get; set; }
+    public long RewardDetailId { get; set; }
+    public int RewardNumber { get; set; }
+}

SVSim.Database/Models/ViewerLeaderSkinSetClaim.cs

@@ -0,0 +1,14 @@
+namespace SVSim.Database.Models;
+
+/// <summary>
+/// One row per (viewer, leader-skin series) marking that the viewer has claimed the
+/// series-completion bonus via /leader_skin/buy_set_item. Composite PK (ViewerId, SeriesId).
+/// Standalone table (not a Viewer owned collection) to avoid the cartesian-explode pitfall
+/// when loading the viewer graph — claim state is checked per-series, not per-viewer-load.
+/// </summary>
+public class ViewerLeaderSkinSetClaim
+{
+    public long ViewerId { get; set; }
+    public int SeriesId { get; set; }
+    public DateTime ClaimedAt { get; set; }
+}