Initial commit: Brass & Sigil monorepo

Self-hosted Minecraft modpack distribution + administration system.

- launcher/  Avalonia 12 desktop client; single-file win-x64 publish.
             Microsoft auth via XboxAuthNet, manifest+SHA-1 mod sync,
             portable install path, sidecar settings.
- server/    brass-sigil-server daemon (.NET 8, linux-x64). Wraps the
             MC subprocess, embedded Kestrel admin panel with cookie
             auth + rate limiting, RCON bridge, scheduled backups,
             BlueMap CLI integration with player markers + skin proxy,
             friend-side whitelist request flow, world wipe with seed
             selection (keep current / random / custom).
- pack/      pack.lock.json (Modrinth + manual CurseForge entries),
             data-only tweak source under tweaks/, build outputs in
             overrides/ (gitignored).
- scripts/   Build-Pack / Build-Tweaks / Update-Pack / Check-Updates
             plus Deploy-Brass.ps1 unified one-shot deploy with
             version-bump pre-flight and daemon-state detection.

server/Commands/SyncCommand.cs

@@ -0,0 +1,32 @@
+using BrassAndSigil.Server.Models;
+using BrassAndSigil.Server.Services;
+using Spectre.Console;
+using Spectre.Console.Cli;
+
+namespace BrassAndSigil.Server.Commands;
+
+public sealed class SyncCommand : AsyncCommand<BaseCommandSettings>
+{
+    public override async Task<int> ExecuteAsync(CommandContext context, BaseCommandSettings settings)
+    {
+        var config = ServerConfig.Load(settings.ConfigPath);
+        AnsiConsole.MarkupLine($"[bold]Syncing[/] from [blue]{config.ManifestUrl}[/]");
+        AnsiConsole.MarkupLine($"[grey]Target: {Path.GetFullPath(config.ServerDir)}[/]");
+        AnsiConsole.MarkupLine("");
+
+        var sync = new ManifestSync();
+        var progress = new Progress<string>(msg => AnsiConsole.MarkupLine($"  [grey]{msg.EscapeMarkup()}[/]"));
+        try
+        {
+            var result = await sync.SyncAsync(config.ManifestUrl, config.ServerDir, progress);
+            AnsiConsole.MarkupLine("");
+            AnsiConsole.MarkupLine($"[green]✓[/] pack v{result.PackVersion} | downloaded={result.Downloaded} removed={result.Removed} client-only-skipped={result.Skipped}");
+            return 0;
+        }
+        catch (Exception ex)
+        {
+            AnsiConsole.MarkupLine($"[red]✗[/] {ex.Message.EscapeMarkup()}");
+            return 1;
+        }
+    }
+}