feat(gui): make desktop setup flow real and testable

Add a GUI-first setup gate and runtime state API so desktop onboarding is safe, iterative, and works with isolated fresh-mode installs. Scaffold and wire the desktop shell/runtime pieces so this branch runs end-to-end without disturbing existing user installs.

apps/gui/scripts/start-dashboard.mjs

@@ -0,0 +1,95 @@
+import { spawn } from "node:child_process";
+import { dirname, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const here = dirname(fileURLToPath(import.meta.url));
+const repoRoot = resolve(here, "../../..");
+const python = process.env.HERMES_PYTHON || "python";
+const port = process.env.HERMES_GUI_PORT || "9120";
+const url = `http://127.0.0.1:${port}`;
+
+async function isHealthy() {
+  try {
+    const res = await fetch(`${url}/api/health`, {
+      signal: AbortSignal.timeout(1000),
+    });
+    const data = await res.json();
+    return res.ok && data.status === "ok";
+  } catch {
+    return false;
+  }
+}
+
+function wslRepoRoot() {
+  const normalized = repoRoot.replaceAll("\\", "/");
+  const parts = normalized.split("/");
+  const host = parts[2]?.toLowerCase();
+  if (process.platform !== "win32") return null;
+  if (host !== "wsl$" && host !== "wsl.localhost") return null;
+  const distro = parts[3];
+  const path = `/${parts.slice(4).join("/")}`;
+  return distro && path !== "/" ? { distro, path } : null;
+}
+
+function spawnDashboard() {
+  const wsl = wslRepoRoot();
+  if (wsl) {
+    return spawn(
+      "wsl.exe",
+      [
+        "-d",
+        wsl.distro,
+        "--cd",
+        wsl.path,
+        "env",
+        "HERMES_GUI=1",
+        process.env.HERMES_WSL_PYTHON || "python",
+        "-m",
+        "hermes_cli.main",
+        "dashboard",
+        "--gui",
+        "--no-open",
+        "--host",
+        "127.0.0.1",
+        "--port",
+        port,
+      ],
+      { stdio: "inherit" },
+    );
+  }
+
+  return spawn(
+    python,
+    [
+      "-m",
+      "hermes_cli.main",
+      "dashboard",
+      "--gui",
+      "--no-open",
+      "--host",
+      "127.0.0.1",
+      "--port",
+      port,
+    ],
+    {
+      cwd: repoRoot,
+      env: {
+        ...process.env,
+        HERMES_GUI: "1",
+      },
+      stdio: "inherit",
+    },
+  );
+}
+
+if (await isHealthy()) {
+  console.log(`Hermes GUI already running -> ${url}`);
+  process.exit(0);
+}
+
+const child = spawnDashboard();
+
+child.on("exit", (code, signal) => {
+  if (signal) process.kill(process.pid, signal);
+  process.exit(code ?? 0);
+});