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
+  }
+]