feat(desktop): ship the CLI as opencode and put it on the Windows PATH - #56897

• The bundled CLI is now opencode / opencode.exe (was opencode-cli) on every platform. That covers resources, staging, the version file, mac signing entitlements, dev builds and the Windows signature check in publish.yml.
• On Windows, typing opencode in any new terminal now runs the desktop's CLI.

Why a link directory

Each version stages its CLI in its own folder (<userData>\cli\<version>-<arch>\), because Windows cannot replace an exe that is still running. Putting that folder on PATH would mean editing PATH on every update. Instead, PATH gets one fixed folder that holds a hard link to the current stage:

flowchart LR
  PATH["User PATH<br/>%APPDATA%\ai.opencode.desktop\bin"] --> link["bin\opencode.exe<br/>(hard link)"]
  link --> stage["cli\2.1.0-x64\opencode.exe"]
  old["cli\2.0.20-x64\opencode.exe"] -. "cleanStages" .-> gone((removed))

• PATH is edited once. It is edited only on the launch that creates bin\. If the user removes the entry, it stays removed.
• No extra disk use. The hard link uses no space, and an update only moves the link. If a hard link is not possible, the app copies the exe instead.
• Safe while the CLI runs. If a terminal is still running the old link, the app renames it to *.old (Windows allows renaming a running exe) and deletes it on a later launch.
• Outside $INSTDIR. The installer stops every process that runs from the install directory. A link there would kill open TUI sessions on every update.
• Existing installs win. The entry goes at the end of the user PATH, so a curl, npm or winget opencode that is already on PATH keeps priority.

PATH editing

cli-path.ts makes a one-time call to Windows PowerShell off the startup path. It reads the raw registry value so %USERPROFILE% entries stay unexpanded and REG_EXPAND_SZ is kept. Then it broadcasts WM_SETTINGCHANGE so Explorer picks up the change:

$key = [Microsoft.Win32.Registry]::CurrentUser.CreateSubKey('Environment')
$entries = @(([string]$key.GetValue('Path', '', 'DoNotExpandEnvironmentNames')) -split ';' | Where-Object { $_ })
if ($entries -contains $directory) { exit 0 }
$key.SetValue('Path', (($entries + $directory) -join ';'), 'ExpandString')
[Environment]::SetEnvironmentVariable('OPENCODE_PATH_REFRESH', $null, 'User')  # broadcasts WM_SETTINGCHANGE

• This avoids setx, which cuts PATH at 1024 characters, and [Environment]::SetEnvironmentVariable('Path', …), which rewrites PATH as REG_SZ.
• A real uninstall (not an update) removes the PATH entry and bin\ in customUnInstall. A reinstall then adds them again.