Don't depend on Node anymore (#346)

## Summary
- package `packages/server` as a standalone desktop executable so
Electron and Tauri no longer depend on a system-installed Node runtime
in production
- align Electron and Tauri startup logic around launching the packaged
server, resolving binaries from the user shell, and bundling the same
server resources into both desktop apps
- replace the workspace instance proxy path that used
`@fastify/reply-from` with a direct streaming proxy so packaged
standalone builds can talk to spawned `opencode` instances correctly

## Why
Desktop production builds were still depending on a user-provided Node
runtime to launch `packages/server`, which made packaging less
self-contained and created different behavior across machines. While
moving to a standalone server executable, we also found that
Bun-compiled standalone builds could start `opencode` successfully but
failed when proxying requests to those instances through `reply-from`.

The goal of this change is to make desktop production startup
self-contained, keep Electron and Tauri behavior aligned, and restore
correct communication with local `opencode` instances in packaged
builds.

## What Changed
- added a standalone build path for `packages/server` and bundle
`codenomad-server` into desktop resources
- updated Electron production startup to resolve and launch the
standalone server executable
- updated Tauri production startup to resolve and launch the standalone
server executable with matching cwd and shell behavior
- added runtime path helpers so the packaged server can reliably find
its bundled UI, auth templates, config template, and package metadata
- improved bare binary resolution so commands like `opencode` can be
resolved from the user's login shell environment
- upgraded the server stack to newer Fastify-compatible packages needed
for the standalone/runtime work
- replaced the workspace instance proxy implementation with a direct
streaming proxy for requests to spawned `opencode` instances
- updated Electron and Tauri build/prebuild scripts to generate and
package the standalone server, while also repairing missing
platform-specific optional binaries during packaging

## Benefits
- desktop production builds no longer require Node to be installed on
the user's system
- Electron and Tauri now use the same packaged server model in
production, reducing platform drift
- packaged desktop apps can successfully create workspaces, launch
`opencode`, and proxy health/session traffic to those instances
- the server bundle is more self-contained and resilient to different
launch environments
- desktop packaging is more predictable because the required server
executable is built and bundled as part of the app build flow

packages/electron-app/electron/main/main.ts

@@ -118,6 +118,8 @@ function loadLoadingScreen(window: BrowserWindow) {
   loader.catch((error) => {
     console.error("[cli] failed to load loading screen:", error)
   })
+
+  return loader
 }
 
 function getAllowedRendererOrigins(window?: BrowserWindow | null): string[] {
@@ -292,7 +294,7 @@ function createWindow() {
   showingLoadingScreen = true
   currentCliUrl = null
   clearWindowAllowedOrigin(window)
-  loadLoadingScreen(window)
+  const loadingReady = loadLoadingScreen(window)
 
   if (process.env.NODE_ENV === "development") {
     window.webContents.openDevTools({ mode: "detach" })
@@ -311,11 +313,7 @@ function createWindow() {
     showingLoadingScreen = false
   })
 
-  if (pendingCliUrl) {
-    const url = pendingCliUrl
-    pendingCliUrl = null
-    startCliPreload(url)
-  }
+  return loadingReady
 }
 
 function showLoadingScreen(force = false) {
@@ -622,7 +620,8 @@ app.whenReady().then(() => {
     // ignore
   }
 
-  startCli()
+  const loadingReady = createWindow()
+  ;(mainWindow as BrowserWindow & { __codenomadOpenRemoteWindow?: typeof openRemoteWindow }).__codenomadOpenRemoteWindow = openRemoteWindow
 
   if (isMac) {
     session.defaultSession.setSpellCheckerEnabled(false)
@@ -639,8 +638,11 @@ app.whenReady().then(() => {
     }
   }
 
-  createWindow()
-  ;(mainWindow as BrowserWindow & { __codenomadOpenRemoteWindow?: typeof openRemoteWindow }).__codenomadOpenRemoteWindow = openRemoteWindow
+  void loadingReady.finally(() => {
+    setTimeout(() => {
+      void startCli()
+    }, 0)
+  })
 
   app.on("certificate-error", (event, _webContents, url, error, _certificate, callback) => {
     if (isInsecureOriginAllowed(url)) {