feat: add Windows ARM64 support with x64-baseline CLI workaround (#2537)

* feat: add Windows ARM64 support with x64-baseline CLI workaround

Windows ARM64 native opencode.exe fails with a Bun FFI/TinyCC dlopen
error (anomalyco/opencode#19130). As a temporary workaround:

- Bundle x64-baseline OpenCode CLI on ARM64 instead of native ARM64
  (prepare-opencode-cli.mjs, env-runtime.js)
- Disable OpenCode self-upgrade on ARM64 in server, VS Code, and UI
  (upgrade-capability.js, opencode-upgrade-runtime.ts, useUIStore.ts,
  OpenCodeCliSettings.tsx, search.ts, SettingsView.tsx, platform.ts)
- Add ARM64 Windows cross-compile builds to release and smoke workflows
  (release.yml, release-desktop-smoke.yml)
- Refactor Windows latest.yml to use combine-electron-manifests pattern
  matching macOS, since two arches now produce per-arch manifests

The CI ARM64 build itself is permanent; only the x64-baseline CLI
bundling and upgrade disablement are temporary and should be reverted
when the upstream issue is resolved.

* fix(desktop): select Windows updater by architecture

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/ui/src/lib/settings/search.ts

@@ -26,6 +26,8 @@ interface SettingsSearchAvailabilityContext extends SettingsRuntimeContext {
   isWindows: boolean;
   // Linux desktop shell — for controls that only render on linux.
   isLinux: boolean;
+  // Windows ARM64 — temporary workaround gate (see opencode#19130).
+  isWindowsArm64: boolean;
 }
 
 const SETTINGS_SEARCH_ITEMS: readonly SettingsSearchItem[] = [
@@ -470,7 +472,7 @@ const SETTINGS_SEARCH_ITEMS: readonly SettingsSearchItem[] = [
     page: 'general',
     titleKey: 'settings.openchamber.opencodeCli.field.showUpdateNotifications',
     keywords: ['opencode', 'cli', 'updates'],
-    isAvailable: (ctx) => !ctx.isVSCode,
+    isAvailable: (ctx) => !ctx.isVSCode && !ctx.isWindowsArm64,
   },
   {
     id: 'sessions.agent-control-tool',