feat: D.6 first-run wizard — detect, start, link, group, gek-init, pair

Desktop client guides new users through the full onboarding sequence
without a terminal: detect local node → start daemon (systemd with
direct-start fallback for dev) → link node key to hub → create group →
attach directories → gek-init → operator pair.

- node:detect returns configured field to distinguish missing vs stopped
- node:start tries systemctl first, checks is-active, falls back to
  spawning the binary directly when the unit crashes (dev mode)
- probeNode() extracts the shared config→token→fetch pattern
- SetupWelcome on empty HomePage links to /create-group
- CreateGroupWizard step 0 handles node detection and start
- platform.js exposes node.installed() and node.start()
- 12 setup.* i18n keys added to all 10 locales
- Integration test for node:start fallback logic

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

1 files changed, 2 insertions, 0 deletions

diff --git a/packages/meshbay-client/src/preload.js b/packages/meshbay-client/src/preload.js
index e9fd375..c8553a5 100644
--- a/packages/meshbay-client/src/preload.js
+++ b/packages/meshbay-client/src/preload.js
@@ -86,6 +86,8 @@ contextBridge.exposeInMainWorld('meshbay', {
   // pattern as hub:fetch.
   node: {
     detect: () => ipcRenderer.invoke('node:detect'),
+    installed: () => ipcRenderer.invoke('node:installed'),
+    start: () => ipcRenderer.invoke('node:start'),
     call: (method, path, body) => ipcRenderer.invoke('node:call', method, path, body),
     pairingCode: () => ipcRenderer.invoke('node:pairing-code'),
     setPairingCode: (code) => ipcRenderer.invoke('node:set-pairing-code', code),