fix(desktop): skip the PowerShell profile probe when node is already resolvable - #5771

💭 I'm reviewing the import conventions for this module. The question is whether to use a named import or namespace import for CommandAvailability from the shell package subpath. Since this is a utility module rather than a service module, and we're only importing a single tag, a named import seems more appropriate here. Looking at the test setup, providing the service as a layer seam is legitimate. The redundancy of yielding CommandAvailability and then re-providing it with Effect.provideService is harmless but worth noting — since it has a default value, this pattern works but could potentially be streamlined. The named import pattern aligns with the repo's conventions for this shared utilities module. CommandAvailability is a Context.Reference that returns an Effect requiring FileSystem and Path dependencies, so using yield* CommandAvailability correctly acquires it from the environment. Providing the service with Effect.provideService(CommandAvailability, commandAvailable) follows the expected pattern, and the test setup appears to be using Layer.succe