feat(discord): add DiscordPermissionChecker for session management rights

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

src/GmRelay.DiscordBot/Infrastructure/Discord/DiscordPermissionChecker.cs

@@ -0,0 +1,32 @@
+namespace GmRelay.DiscordBot.Infrastructure.Discord;
+
+public sealed class DiscordPermissionChecker
+{
+    private const ulong AdministratorPermission = 0x8;
+
+    public bool CanManageSchedule(
+        ulong guildOwnerId,
+        ulong userId,
+        IEnumerable<ulong> userRoles,
+        IEnumerable<ulong> dbManagerUserIds)
+    {
+        if (userId == guildOwnerId)
+            return true;
+
+        if (dbManagerUserIds.Contains(userId))
+            return true;
+
+        return false;
+    }
+
+    public bool CanManageSchedule(ulong guildOwnerId, ulong userId, IEnumerable<ulong> dbManagerUserIds, ulong resolvedPermissions)
+    {
+        if (userId == guildOwnerId)
+            return true;
+
+        if (dbManagerUserIds.Contains(userId))
+            return true;
+
+        return (resolvedPermissions & AdministratorPermission) == AdministratorPermission;
+    }
+}

tests/GmRelay.Bot.Tests/Discord/DiscordPermissionCheckerTests.cs

@@ -0,0 +1,59 @@
+using GmRelay.DiscordBot.Infrastructure.Discord;
+
+namespace GmRelay.Bot.Tests.Discord;
+
+public sealed class DiscordPermissionCheckerTests
+{
+    [Fact]
+    public void CanManageSchedule_WhenUserIsGuildOwner_ReturnsTrue()
+    {
+        var checker = new DiscordPermissionChecker();
+        var result = checker.CanManageSchedule(
+            guildOwnerId: 123456789ul,
+            userId: 123456789ul,
+            userRoles: Array.Empty<ulong>(),
+            dbManagerUserIds: Array.Empty<ulong>());
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void CanManageSchedule_WhenUserHasAdministratorPermission_ReturnsTrue()
+    {
+        var checker = new DiscordPermissionChecker();
+        var result = checker.CanManageSchedule(
+            guildOwnerId: 123456789ul,
+            userId: 987654321ul,
+            dbManagerUserIds: Array.Empty<ulong>(),
+            resolvedPermissions: 0x8); // Administrator
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void CanManageSchedule_WhenUserIsDbManager_ReturnsTrue()
+    {
+        var checker = new DiscordPermissionChecker();
+        var managerId = 555ul;
+        var result = checker.CanManageSchedule(
+            guildOwnerId: 123456789ul,
+            userId: managerId,
+            userRoles: Array.Empty<ulong>(),
+            dbManagerUserIds: new[] { managerId });
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void CanManageSchedule_WhenRegularUser_ReturnsFalse()
+    {
+        var checker = new DiscordPermissionChecker();
+        var result = checker.CanManageSchedule(
+            guildOwnerId: 123456789ul,
+            userId: 111ul,
+            userRoles: Array.Empty<ulong>(),
+            dbManagerUserIds: new[] { 222ul });
+
+        Assert.False(result);
+    }
+}