feat(tutorial): /tutorial/pack_open emits tutorial_step=100, advances viewer state

Stack [HttpPost("/tutorial/pack_open")] alias on PackController.Open. Detect
isTutorialPath via HttpContext.Request.Path; gate the type_detail rejection,
currency switch, open-count tracking, and currency reward_list entries behind
!isTutorialPath so the starter legendary pack (99047/990047, type_detail=5)
bypasses the purchasable-pack code path. After grant, set MissionData.TutorialState=100
and emit tutorial_step=100 in PackOpenResponse — this is the sole END transition,
per live-traffic capture. Add pack 99047 to test-fixture packs.json.

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

SVSim.Bootstrap/Data/test-fixtures/seeds/packs.json

@@ -61,6 +61,46 @@
     ],
     "banners": []
   },
+  {
+    "parent_gacha_id": 99047,
+    "base_pack_id": 90001,
+    "gacha_type": 1,
+    "pack_category": 1,
+    "poster_type": 0,
+    "commence_date": "2026-05-01 02:00:00",
+    "complete_date": "2030-12-31 23:59:59",
+    "sleeve_id": 5090001,
+    "special_sleeve_id": 0,
+    "override_draw_effect_pack_id": 90001,
+    "override_ui_effect_pack_id": 90001,
+    "gacha_detail": "A pack contains 8 cards, including at least one legendary card from Throwback Rotation (Altersphere - Colosseum)!",
+    "is_hide": true,
+    "is_new": false,
+    "is_pre_release": false,
+    "open_count_limit": 0,
+    "sales_period_time": null,
+    "gacha_point": null,
+    "child_gachas": [
+      {
+        "gacha_id": 990047,
+        "type_detail": 5,
+        "cost": 1,
+        "card_count": 8,
+        "item_id": 90001,
+        "is_daily_single": false,
+        "override_increase_gacha_point": 0,
+        "purchase_limit_count": 0,
+        "free_gacha_campaign_id": null,
+        "campaign_name": null
+      }
+    ],
+    "banners": [
+      {
+        "banner_name": "card_pack_99047_dialog",
+        "dialog_title": "Dia_BuyCard_006_Title"
+      }
+    ]
+  },
   {
     "parent_gacha_id": 92001,
     "base_pack_id": 90001,