fix(deck-builder): wire key is cardID/phantomCardID, not snake_case

Client's LitJson serializer emits the C# property name verbatim — the
SetParameter param classes in Wizard/GenerateDeckCodeTask.cs use cardID /
phantomCardID, and the matching Parse() reads jsonData["cardID"]. Snake-case
keys bound to empty in msgpack deserialize, the controller saw 0 cards, and
returned INVALID_DECK — surfaced as a blank deck code in the in-game UI.

Repro lived in data_dumps/traffic.ndjson #19-20. Existing tests pass through
the same JsonPropertyName on both serialize and deserialize, so they happily
round-tripped any consistent key — adding a wire-shape regression test that
posts the literal client JSON would be the right way to catch this class of
bug in the future (out of scope here).

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

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/DeckBuilder/GetDeckFromCodeResponse.cs

@@ -46,7 +46,9 @@ public class DeckPayload
     [Key("rotation_id")]
     public object RotationId { get; set; } = 0;
 
-    [JsonPropertyName("card_id")]
-    [Key("card_id")]
+    // Wire key is camelCase mid-word capital to mirror the client's `cardID` parser
+    // (Wizard/GetDeckDataFromCodeTask.cs:44 reads `jsonData["cardID"]`).
+    [JsonPropertyName("cardID")]
+    [Key("cardID")]
     public List<long> CardID { get; set; } = new();
 }