feat(shared): add GameSystem enum and Showcase DTOs

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

src/GmRelay.Shared/Domain/GameSystem.cs

@@ -0,0 +1,88 @@
+using System.Collections.Frozen;
+
+namespace GmRelay.Shared.Domain;
+
+public enum GameSystem
+{
+    Dnd5e,
+    Dnd3_5,
+    Dnd4e,
+    DnD2024,
+    Pathfinder1e,
+    Pathfinder2e,
+    Starfinder,
+    CallOfCthulhu,
+    WarhammerFantasy,
+    Warhammer40k,
+    DarkHeresy,
+    Shadowrun,
+    GURPS,
+    Fate,
+    SavageWorlds,
+    CyberpunkRed,
+    VampireTheMasquerade,
+    Lancer,
+    BladesInTheDark,
+    DungeonWorld,
+    Numenera,
+    CypherSystem,
+    Other
+}
+
+public static class GameSystemExtensions
+{
+    private static readonly FrozenDictionary<GameSystem, string> DisplayNames =
+        new Dictionary<GameSystem, string>
+        {
+            [GameSystem.Dnd5e] = "D&D 5e",
+            [GameSystem.Dnd3_5] = "D&D 3.5",
+            [GameSystem.Dnd4e] = "D&D 4e",
+            [GameSystem.DnD2024] = "D&D 2024",
+            [GameSystem.Pathfinder1e] = "Pathfinder 1e",
+            [GameSystem.Pathfinder2e] = "Pathfinder 2e",
+            [GameSystem.Starfinder] = "Starfinder",
+            [GameSystem.CallOfCthulhu] = "Call of Cthulhu",
+            [GameSystem.WarhammerFantasy] = "Warhammer Fantasy",
+            [GameSystem.Warhammer40k] = "Warhammer 40,000",
+            [GameSystem.DarkHeresy] = "Dark Heresy",
+            [GameSystem.Shadowrun] = "Shadowrun",
+            [GameSystem.GURPS] = "GURPS",
+            [GameSystem.Fate] = "Fate",
+            [GameSystem.SavageWorlds] = "Savage Worlds",
+            [GameSystem.CyberpunkRed] = "Cyberpunk Red",
+            [GameSystem.VampireTheMasquerade] = "Vampire: The Masquerade",
+            [GameSystem.Lancer] = "Lancer",
+            [GameSystem.BladesInTheDark] = "Blades in the Dark",
+            [GameSystem.DungeonWorld] = "Dungeon World",
+            [GameSystem.Numenera] = "Numenera",
+            [GameSystem.CypherSystem] = "Cypher System",
+            [GameSystem.Other] = "Другое"
+        }.ToFrozenDictionary();
+
+    public static string ToDisplayName(this GameSystem system) =>
+        DisplayNames.TryGetValue(system, out var name) ? name : "Другое";
+
+    public static GameSystem TryParseFuzzy(string input)
+    {
+        if (string.IsNullOrWhiteSpace(input))
+            return GameSystem.Other;
+
+        if (Enum.TryParse<GameSystem>(input, true, out var exact))
+            return exact;
+
+        foreach (var system in Enum.GetValues<GameSystem>())
+        {
+            if (system == GameSystem.Other)
+                continue;
+
+            var name = system.ToString();
+            if (name.Contains(input, StringComparison.OrdinalIgnoreCase) ||
+                input.Contains(name, StringComparison.OrdinalIgnoreCase))
+            {
+                return system;
+            }
+        }
+
+        return GameSystem.Other;
+    }
+}

src/GmRelay.Shared/Features/Showcase/ShowcaseFilter.cs

@@ -0,0 +1,23 @@
+namespace GmRelay.Shared.Features.Showcase;
+
+public sealed record ShowcaseFilter(
+    DateFilter Date = DateFilter.All,
+    SeatFilter Seats = SeatFilter.Any,
+    string? System = null,
+    bool? IsOneShot = null,
+    string? Format = null);
+
+public enum DateFilter
+{
+    Today,
+    Tomorrow,
+    ThisWeek,
+    All
+}
+
+public enum SeatFilter
+{
+    Available,
+    Waitlist,
+    Any
+}

src/GmRelay.Shared/Features/Showcase/ShowcaseSessionDto.cs

@@ -0,0 +1,19 @@
+namespace GmRelay.Shared.Features.Showcase;
+
+public sealed record ShowcaseSessionDto(
+    Guid Id,
+    Guid GroupId,
+    string GroupName,
+    string? GroupSlug,
+    string Title,
+    DateTime ScheduledAt,
+    string Status,
+    string? System,
+    bool IsOneShot,
+    string? Format,
+    int? DurationMinutes,
+    string? CoverImageUrl,
+    int? MaxPlayers,
+    int ActivePlayerCount,
+    int WaitlistedPlayerCount,
+    bool AllowDirectRegistration);