refactor: move setup scripts out of src/ to reduce build token count

Setup scripts are standalone CLI tools run via tsx with no runtime
imports from the main app. Moving them out of src/ excludes them from
the tsc build output and reduces the compiled bundle size.

- git mv src/setup/ setup/
- Fix imports to use ../src/logger.js and ../src/config.js
- Update package.json, vitest.config.ts, SKILL.md references
- Fix platform tests to be cross-platform (macOS + Linux)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

setup/platform.ts

@@ -0,0 +1,130 @@
+/**
+ * Cross-platform detection utilities for NanoClaw setup.
+ */
+import { execSync } from 'child_process';
+import fs from 'fs';
+import os from 'os';
+
+export type Platform = 'macos' | 'linux' | 'unknown';
+export type ServiceManager = 'launchd' | 'systemd' | 'none';
+
+export function getPlatform(): Platform {
+  const platform = os.platform();
+  if (platform === 'darwin') return 'macos';
+  if (platform === 'linux') return 'linux';
+  return 'unknown';
+}
+
+export function isWSL(): boolean {
+  if (os.platform() !== 'linux') return false;
+  try {
+    const release = fs.readFileSync('/proc/version', 'utf-8').toLowerCase();
+    return release.includes('microsoft') || release.includes('wsl');
+  } catch {
+    return false;
+  }
+}
+
+export function isRoot(): boolean {
+  return process.getuid?.() === 0;
+}
+
+export function isHeadless(): boolean {
+  // No display server available
+  if (getPlatform() === 'linux') {
+    return !process.env.DISPLAY && !process.env.WAYLAND_DISPLAY;
+  }
+  // macOS is never headless in practice (even SSH sessions can open URLs)
+  return false;
+}
+
+export function hasSystemd(): boolean {
+  if (getPlatform() !== 'linux') return false;
+  try {
+    // Check if systemd is PID 1
+    const init = fs.readFileSync('/proc/1/comm', 'utf-8').trim();
+    return init === 'systemd';
+  } catch {
+    return false;
+  }
+}
+
+/**
+ * Open a URL in the default browser, cross-platform.
+ * Returns true if the command was attempted, false if no method available.
+ */
+export function openBrowser(url: string): boolean {
+  try {
+    const platform = getPlatform();
+    if (platform === 'macos') {
+      execSync(`open ${JSON.stringify(url)}`, { stdio: 'ignore' });
+      return true;
+    }
+    if (platform === 'linux') {
+      // Try xdg-open first, then wslview for WSL
+      if (commandExists('xdg-open')) {
+        execSync(`xdg-open ${JSON.stringify(url)}`, { stdio: 'ignore' });
+        return true;
+      }
+      if (isWSL() && commandExists('wslview')) {
+        execSync(`wslview ${JSON.stringify(url)}`, { stdio: 'ignore' });
+        return true;
+      }
+      // WSL without wslview: try cmd.exe
+      if (isWSL()) {
+        try {
+          execSync(`cmd.exe /c start "" ${JSON.stringify(url)}`, { stdio: 'ignore' });
+          return true;
+        } catch {
+          // cmd.exe not available
+        }
+      }
+    }
+  } catch {
+    // Command failed
+  }
+  return false;
+}
+
+export function getServiceManager(): ServiceManager {
+  const platform = getPlatform();
+  if (platform === 'macos') return 'launchd';
+  if (platform === 'linux') {
+    if (hasSystemd()) return 'systemd';
+    return 'none';
+  }
+  return 'none';
+}
+
+export function getNodePath(): string {
+  try {
+    return execSync('command -v node', { encoding: 'utf-8' }).trim();
+  } catch {
+    return process.execPath;
+  }
+}
+
+export function commandExists(name: string): boolean {
+  try {
+    execSync(`command -v ${name}`, { stdio: 'ignore' });
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+export function getNodeVersion(): string | null {
+  try {
+    const version = execSync('node --version', { encoding: 'utf-8' }).trim();
+    return version.replace(/^v/, '');
+  } catch {
+    return null;
+  }
+}
+
+export function getNodeMajorVersion(): number | null {
+  const version = getNodeVersion();
+  if (!version) return null;
+  const major = parseInt(version.split('.')[0], 10);
+  return isNaN(major) ? null : major;
+}