feat: import/export settings, send backup of settings when leaving guild

Catalogger.Backend/Database/Repositories/InviteRepository.cs

@@ -65,6 +65,34 @@ public class InviteRepository(ILogger logger, DatabaseConnection conn)
             new { GuildId = guildId.Value, Code = code }
         );
 
+    /// <summary>
+    /// Bulk imports an array of invite codes and names.
+    /// The GuildId property in the Invite object is ignored.
+    /// </summary>
+    public async Task ImportInvitesAsync(Snowflake guildId, IEnumerable<Invite> invites)
+    {
+        await using var tx = await conn.BeginTransactionAsync();
+        foreach (var invite in invites)
+        {
+            await conn.ExecuteAsync(
+                """
+                insert into invites (code, guild_id, name)
+                values (@Code, @GuildId, @Name) on conflict (code)
+                    do update set name = @Name
+                """,
+                new
+                {
+                    GuildId = guildId.Value,
+                    invite.Code,
+                    invite.Name,
+                },
+                transaction: tx
+            );
+        }
+
+        await tx.CommitAsync();
+    }
+
     public void Dispose()
     {
         conn.Dispose();