Add Spinner, a Minecraft hostname-routing reverse proxy

Routes Java Edition connections by the hostname in the handshake, with
wildcard domains, backend failover, PROXY protocol v2, cached server-list
status from health probes, hot-reloaded config, and an admin page and
metrics endpoint. Includes CI, tagged releases and a container image.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

scripts/lint-design.mjs

@@ -0,0 +1,57 @@
+// Style gate for the dashboard, following the Lightwell design language (see docs/design.md).
+// Fails on em or en dashes, emoji, exclamation marks in interface copy, and raw colors outside the
+// token block of web/index.html. Run with: node scripts/lint-design.mjs
+import { readdirSync, readFileSync, statSync } from "node:fs";
+import { extname, join, relative, sep } from "node:path";
+
+const root = new URL("..", import.meta.url).pathname.replace(/^\/([A-Za-z]:)/, "$1");
+const targets = ["web", "docs", "cmd", "internal", "scripts", "README.md", ".gitea", "."];
+const skipDirs = new Set(["node_modules", ".git"]);
+const exts = new Set([".html", ".md", ".go", ".sh", ".mjs", ".json", ".yml", ".example"]);
+
+const dash = /[–—−]/;
+const emoji = /[\u{1F300}-\u{1FAFF}\u{2600}-\u{27BF}\u{1F900}-\u{1F9FF}\u{FE0F}\u{2B50}\u{2705}\u{274C}]/u;
+const rawColor = /#[0-9a-fA-F]{3,8}\b|\brgba?\(|\bhsla?\(/;
+
+const seen = new Set();
+function* walk(p, top) {
+  const st = statSync(p, { throwIfNoEntry: false });
+  if (!st || seen.has(p)) return;
+  if (st.isFile()) { seen.add(p); return yield p; }
+  for (const name of readdirSync(p)) {
+    if (skipDirs.has(name) || (top && name.startsWith(".") && name !== ".gitea")) continue;
+    const full = join(p, name);
+    // the "." target only contributes the files at the top level
+    if (p === root && statSync(full).isDirectory()) continue;
+    yield* walk(full, false);
+  }
+}
+
+const problems = [];
+for (const t of targets) {
+  for (const file of walk(join(root, t), true)) {
+    if (!exts.has(extname(file)) && !file.endsWith(".env.example")) continue;
+    const rel = relative(root, file).split(sep).join("/");
+    if (rel.endsWith("go.sum") || rel === "spinner.example.json" || rel.endsWith("_test.go") || rel === "scripts/lint-design.mjs") continue;
+    const isPage = rel.startsWith("web/") && rel.endsWith(".html");
+    let inTokens = false;
+    readFileSync(file, "utf8").split("\n").forEach((line, i) => {
+      const at = (msg) => problems.push(`${rel}:${i + 1}: ${msg}`);
+      if (line.includes("tokens:begin")) inTokens = true;
+      if (dash.test(line)) at("em dash, en dash or minus sign. Use a comma, colon, period or the word to.");
+      if (emoji.test(line)) at("emoji or pictographic symbol. Use an approved outline icon.");
+      if (isPage && !inTokens && rawColor.test(line.replace(/\/\*.*?\*\//g, "")) && !/placeholder|href="#|&#/.test(line)) {
+        at("raw color outside the token block. Use a token.");
+      }
+      if (isPage && /(?:toast|textContent\s*=|class:'(?:empty|notice)')[^;\n]*'[^']*[A-Za-z]![^']*'/.test(line)) at("exclamation mark in interface copy.");
+      if (line.includes("tokens:end")) inTokens = false;
+    });
+  }
+}
+
+if (problems.length) {
+  console.error(problems.join("\n"));
+  console.error(`\n${problems.length} style problem(s).`);
+  process.exit(1);
+}
+console.log("Style checks passed.");