feat(guild_chat): deck + replay attachments

Implement all five guild_chat attachment endpoints:
- add_deck: server looks up deck by (viewerId, format, deckNo) and snapshots
  the current state into a DECK-type chat message DeckPayload column.
- delete_deck: author OR leader/sub-leader may clear; returns refreshed
  deck_log. Extended IGuildChatMessageRepository.ClearDeckAsync with
  leaderOverride flag; added GetDeckMessagesAsync + GetByMessageIdAsync.
- add_replay: stores {"battle_id": N} in ReplayPayload; full shape is
  TODO(post-merge) pending replay-subsystem capture.
- replay_detail: returns the stored ReplayPayload as JsonElement passthrough.
- deck_log: returns all active DECK messages grouped by API-side Format string
  key ("1"=Rotation, "2"=Unlimited, "3"=PreRotation always present;
  "4"=Crossover, "5"=MyRotation only when non-empty).

Adds DeckLogDataDto (typed) for deck_log / delete_deck responses.
Replay response uses JsonElement passthrough (TODO(post-merge)).
8 new integration tests — all green. Full suite 1530/1530 pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SVSim.Database/Services/Guild/GuildChatService.cs

@@ -1,5 +1,8 @@
+using System.Text.Json;
 using SVSim.Database.Entities.Guild;
+using SVSim.Database.Enums;
 using SVSim.Database.Models.Config;
+using SVSim.Database.Repositories.Deck;
 using SVSim.Database.Repositories.Guild;
 using SVSim.Database.Services;
 
@@ -10,15 +13,18 @@ public sealed class GuildChatService : IGuildChatService
     private readonly IGuildMemberRepository _members;
     private readonly IGuildChatMessageRepository _msgs;
     private readonly IGameConfigService _cfg;
+    private readonly IDeckRepository _decks;
 
     public GuildChatService(
         IGuildMemberRepository members,
         IGuildChatMessageRepository msgs,
-        IGameConfigService cfg)
+        IGameConfigService cfg,
+        IDeckRepository decks)
     {
         _members = members;
         _msgs    = msgs;
         _cfg     = cfg;
+        _decks   = decks;
     }
 
     // ── System-event emission ────────────────────────────────────────────────
@@ -98,18 +104,108 @@ public sealed class GuildChatService : IGuildChatService
         return new(true, stored.MessageId);
     }
 
-    public Task<ChatPostResult> PostDeckAsync(long viewerId, string deckPayloadJson, CancellationToken ct = default)
-        => throw new NotImplementedException();
+    // ── Deck attachment ──────────────────────────────────────────────────────
 
-    public Task<bool> DeleteDeckAsync(long viewerId, int messageId, CancellationToken ct = default)
-        => throw new NotImplementedException();
+    public async Task<ChatPostResult> PostDeckAsync(long viewerId, Format format, int deckFormatApi, int deckNo, CancellationToken ct = default)
+    {
+        var m = await _members.GetMembershipAsync(viewerId, ct);
+        if (m is null) return new(false, null);
 
-    public Task<ChatPostResult> PostReplayAsync(long viewerId, string replayPayloadJson, CancellationToken ct = default)
-        => throw new NotImplementedException();
+        var deck = await _decks.GetDeck(viewerId, format, deckNo);
+        if (deck is null) return new(false, null);
 
-    public Task<string?> GetReplayDetailAsync(long viewerId, int messageId, CancellationToken ct = default)
-        => throw new NotImplementedException();
+        // Build the deck payload JSON that the client expects to parse via DeckLogData / DeckData.Initialize.
+        // Fields: deck_format (API int), deck_no, deck_name, class_id, sleeve_id, leader_skin_id, card_id_array.
+        var cardIdArray = deck.Cards
+            .SelectMany(c => Enumerable.Repeat(c.Card.Id, c.Count))
+            .ToList();
 
-    public Task<string?> GetDeckLogAsync(long viewerId, int messageId, CancellationToken ct = default)
-        => throw new NotImplementedException();
+        var payload = new
+        {
+            deck_format     = deckFormatApi,
+            deck_no         = deck.Number,
+            deck_name       = deck.Name,
+            class_id        = deck.Class.Id,
+            sleeve_id       = (long)deck.Sleeve.Id,
+            leader_skin_id  = deck.LeaderSkin.Id,
+            card_id_array   = cardIdArray,
+        };
+        var payloadJson = JsonSerializer.Serialize(payload);
+
+        var stored = await _msgs.AppendAsync(new GuildChatMessage
+        {
+            GuildId        = m.GuildId,
+            AuthorViewerId = viewerId,
+            MessageType    = GuildChatMessageType.Deck,
+            Body           = "",
+            DeckPayload    = payloadJson,
+            CreatedAt      = DateTime.UtcNow,
+        }, ct);
+        return new(true, stored.MessageId);
+    }
+
+    public async Task<(bool Ok, DeckLogResult? Log)> DeleteDeckAsync(long viewerId, int messageId, CancellationToken ct = default)
+    {
+        var m = await _members.GetMembershipAsync(viewerId, ct);
+        if (m is null) return (false, null);
+
+        bool isLeader = m.Role is GuildRole.Leader or GuildRole.SubLeader;
+        bool cleared  = await _msgs.ClearDeckAsync(m.GuildId, messageId, viewerId, isLeader, ct);
+        if (!cleared) return (false, null);
+
+        var log = await BuildDeckLogAsync(m.GuildId, ct);
+        return (true, log);
+    }
+
+    // ── Replay attachment ────────────────────────────────────────────────────
+
+    public async Task<ChatPostResult> PostReplayAsync(long viewerId, long battleId, CancellationToken ct = default)
+    {
+        var m = await _members.GetMembershipAsync(viewerId, ct);
+        if (m is null) return new(false, null);
+
+        // Store minimal payload; replay subsystem detail is TODO(post-merge).
+        var payloadJson = JsonSerializer.Serialize(new { battle_id = battleId });
+
+        var stored = await _msgs.AppendAsync(new GuildChatMessage
+        {
+            GuildId        = m.GuildId,
+            AuthorViewerId = viewerId,
+            MessageType    = GuildChatMessageType.Replay,
+            Body           = "",
+            ReplayPayload  = payloadJson,
+            CreatedAt      = DateTime.UtcNow,
+        }, ct);
+        return new(true, stored.MessageId);
+    }
+
+    public async Task<string?> GetReplayDetailAsync(long viewerId, int messageId, CancellationToken ct = default)
+    {
+        var m = await _members.GetMembershipAsync(viewerId, ct);
+        if (m is null) return null;
+
+        var msg = await _msgs.GetByMessageIdAsync(m.GuildId, messageId, ct);
+        return msg?.ReplayPayload;
+    }
+
+    // ── Deck log ─────────────────────────────────────────────────────────────
+
+    public async Task<DeckLogResult?> GetDeckLogAsync(long viewerId, CancellationToken ct = default)
+    {
+        var m = await _members.GetMembershipAsync(viewerId, ct);
+        if (m is null) return null;
+        return await BuildDeckLogAsync(m.GuildId, ct);
+    }
+
+    // ── Private helpers ──────────────────────────────────────────────────────
+
+    private async Task<DeckLogResult> BuildDeckLogAsync(int guildId, CancellationToken ct)
+    {
+        var deckMessages = await _msgs.GetDeckMessagesAsync(guildId, ct);
+        var entries = deckMessages
+            .Where(msg => msg.DeckPayload is not null)
+            .Select(msg => new DeckLogEntry(msg.MessageId, msg.AuthorViewerId, msg.DeckPayload!))
+            .ToList();
+        return new DeckLogResult(entries);
+    }
 }