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/wwwroot/modules/modal.js

@@ -0,0 +1,57 @@
+// Tiny modal helper. Registers a single document-level Esc + backdrop-click
+// handler so individual modals don't have to. Public API: openModal(id) /
+// closeModal(id) / closeAllModals().
+"use strict";
+
+let bound = false;
+
+function bindGlobal() {
+    if (bound) return;
+    bound = true;
+    document.addEventListener("keydown", e => {
+        if (e.key === "Escape") closeAllModals();
+    });
+    document.addEventListener("click", e => {
+        // Backdrop click closes the topmost open modal.
+        const backdrop = e.target.closest(".modal-backdrop");
+        if (backdrop) closeModal(backdrop.parentElement.id);
+        const closeBtn = e.target.closest(".modal-close");
+        if (closeBtn) closeModal(closeBtn.closest(".modal").id);
+    });
+}
+
+export function openModal(id) {
+    bindGlobal();
+    const m = document.getElementById(id);
+    if (!m) return;
+    m.hidden = false;
+    document.body.classList.add("modal-open");
+    // Focus first input/button for keyboard users.
+    setTimeout(() => {
+        const focusable = m.querySelector("input, button:not(.modal-close), select, textarea");
+        focusable?.focus();
+    }, 50);
+}
+
+export function closeModal(id) {
+    const m = document.getElementById(id);
+    if (!m) return;
+    m.hidden = true;
+    if (!document.querySelector(".modal:not([hidden])")) {
+        document.body.classList.remove("modal-open");
+    }
+}
+
+export function closeAllModals() {
+    document.querySelectorAll(".modal:not([hidden])").forEach(m => m.hidden = true);
+    document.body.classList.remove("modal-open");
+}
+
+/// Wires `data-open-modal="someId"` on any element to opening the modal.
+export function setupModalTriggers() {
+    bindGlobal();
+    document.addEventListener("click", e => {
+        const trigger = e.target.closest("[data-open-modal]");
+        if (trigger) openModal(trigger.getAttribute("data-open-modal"));
+    });
+}