feat(missions): common DTOs (UserMission, UserAchievement, BPMonthlyMission, MissionInfoData)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

SVSim.EmulatedEntrypoint/Models/Dtos/Common/Mission/MissionInfoDataDto.cs

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+using System.Text.Json.Serialization;
+using MessagePack;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Common.Mission;
+
+/// <summary>
+/// Top-level payload for /mission/info responses (also reused by /mission/retire,
+/// /mission/change_receive_setting; /achievement/receive_reward adds reward_list +
+/// total_receive_count_list to this shape via inheritance).
+///
+/// CanChangeMissionTime is wire-required to be present (capture shows null when active).
+/// Override [JsonIgnore(Condition = Never)] per memory project_wire_null_policy.
+/// </summary>
+[MessagePackObject(keyAsPropertyName: true)]
+public class MissionInfoDataDto
+{
+    [Key(0)][JsonPropertyName("user_mission_list")] public List<UserMissionDto> UserMissionList { get; set; } = new();
+    [Key(1)][JsonPropertyName("is_change_mission")] public bool IsChangeMission { get; set; }
+
+    [Key(2)]
+    [JsonPropertyName("can_change_mission_time")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.Never)]
+    public long? CanChangeMissionTime { get; set; }
+
+    [Key(3)][JsonPropertyName("is_change_receive_type")] public bool IsChangeReceiveType { get; set; }
+
+    [Key(4)]
+    [JsonPropertyName("can_change_receive_type_time")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.Never)]
+    public long? CanChangeReceiveTypeTime { get; set; }
+
+    [Key(5)][JsonPropertyName("user_achievement_list")] public List<UserAchievementDto> UserAchievementList { get; set; } = new();
+    [Key(6)][JsonPropertyName("mission_receive_type")] public string MissionReceiveType { get; set; } = "0";
+
+    [Key(7)]
+    [JsonPropertyName("battle_pass_monthly_mission")]
+    public BPMonthlyMissionsDto? BattlePassMonthlyMission { get; set; }
+}