feat(dashboard): native host onboarding when disconnected

- Add install-command helper (getInstallCommand + platform detection)
  with OS-specific one-liners and configurable base URL
- Show onboarding card on Overview when !hostConnected: copy button,
  platform switcher (macOS/Linux / Windows), and "Check again" button
- "Check again" triggers refresh and shows success/disconnected toast
- refresh() returns state so callers can react to hostConnected
- Add unit tests for install-commands (all platforms, base URL)
- Document "Native host not found" flow in README and INSTALLATION

extension/dashboard/pages/overview.js

@@ -2,8 +2,9 @@
  * Overview page — summary stats, quick-action cards, and virtualized connection lists.
  * Uses the OvList class for infinite-scroll, searchable tables of connections and servers.
  * Depends on: core/utils.js ($, escapeHtml), ui/state-tag.js (stateTag),
- *             ui/modal.js (openModal), pages/ssh.js (openAddSshModal),
- *             pages/rdp.js (openAddRdpModal), core/state.js (sshConnections, rdpConnections)
+ *             ui/modal.js (openModal), ui/toast.js (copyToClipboard, showToast),
+ *             pages/ssh.js (openAddSshModal), pages/rdp.js (openAddRdpModal),
+ *             core/state.js (sshConnections, rdpConnections), data/install-commands.js (getInstallCommand, detectPlatform, INSTALL_SCRIPT_BASE_URL)
  */
 
 const OV_PAGE = 20; // rows per page
@@ -89,6 +90,22 @@ let _ovSvc     = null;
 let _ovSsh     = null;
 let _ovRdp     = null;
 
+/** Current platform for onboarding card (win32 | macos | linux). Set by detectPlatform or switcher. */
+let _onboardingPlatform = null;
+
+/**
+ * Update the onboarding card command and label for the given platform.
+ * @param {'macos'|'linux'|'win32'} platform
+ */
+function _updateOnboardingCommand(platform) {
+  if (typeof getInstallCommand === 'undefined' || typeof INSTALL_SCRIPT_BASE_URL === 'undefined') return;
+  const { label, command } = getInstallCommand(INSTALL_SCRIPT_BASE_URL, platform);
+  const labelEl = $('onboardingPlatformLabel');
+  const cmdEl = $('onboardingCommand');
+  if (labelEl) labelEl.textContent = label;
+  if (cmdEl) cmdEl.textContent = command;
+}
+
 /**
  * Create and wire up the OvList instances for virtual hosts and server tunnels.
  * Called once during dashboard initialisation.
@@ -188,6 +205,41 @@ function initOvLists() {
   $('qaAddSsh')    ?.addEventListener('click', () => openAddSshModal(null));
   $('qaAddRdp')    ?.addEventListener('click', () => openAddRdpModal(null));
   $('qaInstallCA') ?.addEventListener('click', () => openModal('modal-installCA'));
+
+  // Onboarding card (native host not found): Copy, Check again, platform switcher
+  const copyBtn = $('onboardingCopyBtn');
+  if (copyBtn) {
+    copyBtn.addEventListener('click', () => {
+      const cmdEl = $('onboardingCommand');
+      if (cmdEl && typeof copyToClipboard === 'function') copyToClipboard(cmdEl.textContent, copyBtn);
+    });
+  }
+  const checkAgainBtn = $('onboardingCheckAgainBtn');
+  if (checkAgainBtn) {
+    checkAgainBtn.addEventListener('click', async () => {
+      if (typeof refresh !== 'function') return;
+      const state = await refresh();
+      if (state?.hostConnected) {
+        if (typeof showToast === 'function') showToast('Native host connected', 'success');
+      } else {
+        if (typeof showToast === 'function') showToast('Still disconnected. Install the native host using the command above.', 'default');
+      }
+    });
+  }
+  const switchMacLinux = $('onboardingSwitchMacLinux');
+  if (switchMacLinux) {
+    switchMacLinux.addEventListener('click', () => {
+      _onboardingPlatform = 'macos';
+      _updateOnboardingCommand('macos');
+    });
+  }
+  const switchWin = $('onboardingSwitchWin');
+  if (switchWin) {
+    switchWin.addEventListener('click', () => {
+      _onboardingPlatform = 'win32';
+      _updateOnboardingCommand('win32');
+    });
+  }
 }
 
 /**
@@ -251,6 +303,19 @@ function updateDashboard(state) {
   const lu = $('overviewLastUpdated');
   if (lu) lu.textContent = 'Updated ' + new Date().toLocaleTimeString();
 
+  // Onboarding card: show when native host is disconnected
+  const onboardingEl = $('onboardingNativeHost');
+  if (onboardingEl) {
+    if (!state.hostConnected) {
+      onboardingEl.style.display = 'block';
+      if (_onboardingPlatform == null && typeof detectPlatform === 'function') _onboardingPlatform = detectPlatform();
+      _updateOnboardingCommand(_onboardingPlatform || 'linux');
+    } else {
+      onboardingEl.style.display = 'none';
+      _onboardingPlatform = null;
+    }
+  }
+
   setText('swarmCount',         servers.length);
   setText('connCount',          virtualHosts.length);
   setText('serviceTunnelCount', serviceTunnels.length);