feat(item-purchase): /item_purchase/{info,purchase} + catalog

Schema: ItemPurchaseCatalogEntry (single table). Per-viewer quota tracked
via existing ViewerEventCounter keyed by "item_purchase:<id>" with period
JstPeriod.MonthKey when IsMonthlyReset else AllTime.

Controller:
- /info returns catalog + per-period rest (server-computed
  max(0, PurchaseLimit - counter)) + user_card_pack_ticket_list (every
  Items.Type==2 row joined to viewer count, zeros included — client
  unconditionally UpdateItemNum's each entry).
- /purchase: sold_out check before currency check (no counter increment
  on currency failure), inline TryDebit covers RedEther/Crystal/Rupy/Item
  with post-state-total reward_list entry, grant via RewardGrantService.
  Request `rest` accepted but ignored (server counter is canonical).

Importer mirrors PaymentItemImporter shape — idempotent find-or-create,
seed-missing rows preserved. 3 entries from the prod capture.

486 tests pass (was 476; +10 item_purchase tests).

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

SVSim.Bootstrap/Data/seeds/item-purchase.json

@@ -0,0 +1,38 @@
+[
+  {
+    "purchase_id": 1,
+    "require_item_type": 1,
+    "require_item_id": 0,
+    "require_item_num": 5000,
+    "purchase_item_type": 4,
+    "purchase_item_id": 1000,
+    "purchase_item_num": 1,
+    "purchase_name": "[b]One Time Only![/b] Seer's Globe x1",
+    "is_monthly_reset": false,
+    "purchase_limit": 1
+  },
+  {
+    "purchase_id": 100002,
+    "require_item_type": 4,
+    "require_item_id": 1001,
+    "require_item_num": 5,
+    "purchase_item_type": 4,
+    "purchase_item_id": 1000,
+    "purchase_item_num": 1,
+    "purchase_name": "",
+    "is_monthly_reset": true,
+    "purchase_limit": 3
+  },
+  {
+    "purchase_id": 100003,
+    "require_item_type": 1,
+    "require_item_id": 0,
+    "require_item_num": 30000,
+    "purchase_item_type": 4,
+    "purchase_item_id": 1000,
+    "purchase_item_num": 1,
+    "purchase_name": "",
+    "is_monthly_reset": true,
+    "purchase_limit": 10
+  }
+]

SVSim.Bootstrap/Importers/ItemPurchaseImporter.cs

@@ -0,0 +1,59 @@
+using Microsoft.EntityFrameworkCore;
+using SVSim.Bootstrap.Models.Seed;
+using SVSim.Database;
+using SVSim.Database.Models;
+
+namespace SVSim.Bootstrap.Importers;
+
+/// <summary>
+/// Idempotent upsert of the item-purchase catalog from <c>seeds/item-purchase.json</c>.
+/// Source is the wire <c>/item_purchase/info</c> response, extracted via
+/// <c>data_dumps/extract/extract-item-purchase.py</c>. Rows missing from the seed are LEFT INTACT.
+/// </summary>
+public class ItemPurchaseImporter
+{
+    public async Task<int> ImportAsync(SVSimDbContext context, string seedDir)
+    {
+        string path = Path.Combine(seedDir, "item-purchase.json");
+        var seed = SeedLoader.LoadList<ItemPurchaseSeed>(path);
+        if (seed.Count == 0)
+        {
+            Console.WriteLine("[ItemPurchaseImporter] No seed rows; skipping.");
+            return 0;
+        }
+
+        var existing = await context.ItemPurchaseCatalog.ToDictionaryAsync(e => e.Id);
+        int created = 0, updated = 0;
+
+        foreach (var s in seed)
+        {
+            if (s.PurchaseId == 0) continue;
+
+            var entry = existing.TryGetValue(s.PurchaseId, out var ex)
+                ? ex : new ItemPurchaseCatalogEntry { Id = s.PurchaseId };
+
+            entry.RequireItemType = s.RequireItemType;
+            entry.RequireItemId = s.RequireItemId;
+            entry.RequireItemNum = s.RequireItemNum;
+            entry.PurchaseItemType = s.PurchaseItemType;
+            entry.PurchaseItemId = s.PurchaseItemId;
+            entry.PurchaseItemNum = s.PurchaseItemNum;
+            entry.PurchaseName = s.PurchaseName;
+            entry.IsMonthlyReset = s.IsMonthlyReset;
+            entry.PurchaseLimit = s.PurchaseLimit;
+            entry.IsEnabled = true;
+
+            if (ex is null)
+            {
+                context.ItemPurchaseCatalog.Add(entry);
+                existing[s.PurchaseId] = entry;
+                created++;
+            }
+            else updated++;
+        }
+
+        await context.SaveChangesAsync();
+        Console.WriteLine($"[ItemPurchaseImporter] +{created}/~{updated}");
+        return created + updated;
+    }
+}

SVSim.Bootstrap/Models/Seed/ItemPurchaseSeed.cs

@@ -0,0 +1,17 @@
+using System.Text.Json.Serialization;
+
+namespace SVSim.Bootstrap.Models.Seed;
+
+public sealed class ItemPurchaseSeed
+{
+    [JsonPropertyName("purchase_id")] public int PurchaseId { get; set; }
+    [JsonPropertyName("require_item_type")] public int RequireItemType { get; set; }
+    [JsonPropertyName("require_item_id")] public long RequireItemId { get; set; }
+    [JsonPropertyName("require_item_num")] public int RequireItemNum { get; set; }
+    [JsonPropertyName("purchase_item_type")] public int PurchaseItemType { get; set; }
+    [JsonPropertyName("purchase_item_id")] public long PurchaseItemId { get; set; }
+    [JsonPropertyName("purchase_item_num")] public int PurchaseItemNum { get; set; }
+    [JsonPropertyName("purchase_name")] public string PurchaseName { get; set; } = "";
+    [JsonPropertyName("is_monthly_reset")] public bool IsMonthlyReset { get; set; }
+    [JsonPropertyName("purchase_limit")] public int PurchaseLimit { get; set; }
+}

SVSim.Bootstrap/Program.cs

@@ -99,6 +99,7 @@ public static class Program
             await new PaymentItemImporter().ImportAsync(context, opts.SeedDir);
             await new ItemImporter().ImportAsync(context, opts.SeedDir);
             await new SleeveShopImporter().ImportAsync(context, opts.SeedDir);
+            await new ItemPurchaseImporter().ImportAsync(context, opts.SeedDir);
             var puzzleImporter = new PuzzleImporter();
             await puzzleImporter.ImportGroupsAsync(context, opts.SeedDir);
             await puzzleImporter.ImportPuzzlesAsync(context, opts.SeedDir);