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/web/server/lib/opencode/upgrade-capability.js

@@ -1,9 +1,23 @@
+// TEMPORARY WORKAROUND — Windows ARM64: native opencode.exe fails with a Bun
+// FFI/TinyCC dlopen error (https://github.com/anomalyco/opencode/issues/19130).
+// Disable OpenCode self-upgrade on ARM64 so it can't overwrite the working x64
+// binary with the broken ARM64 build. Remove when the upstream issue is resolved.
+const isWindowsArm64 = () => process.platform === 'win32' && process.arch === 'arm64';
+
 export const resolveOpenCodeUpgradeCapability = ({
   isExternal,
   hasManagedProcess,
   activeBinary,
   isBundledBinary,
 }) => {
+  if (isWindowsArm64()) {
+    return {
+      supported: false,
+      manager: 'openchamber',
+      reason: 'windows-arm64-workaround',
+    };
+  }
+
   if (isExternal) {
     return {
       supported: false,