fix: boot and focus simulators via Device Hub URL scheme on Xcode 27+

[hansemannn]

Follow-up to #260.

Why

Device Hub (the Simulator app replacement on Xcode 27+) ignores the legacy -CurrentDeviceUDID argument and does not boot any simulator on launch. Spawning it the old way neither boots nor selects the requested device — launches only worked when Device Hub happened to be running already (that path boots via simctl), and even then only the app itself was focused, never the requested device.

How

• Boot + select: on Device Hub, boot the simulator via simctl boot, then open the device's window using Device Hub's devices://device/open?id=<udid> URL scheme, invoked as open -a <DeviceHub.app> <url> so the Device Hub of the selected Xcode handles it. A failure to open the window is not fatal (the simulator keeps running headless).
• Focus: focus the device window via the same URL scheme instead of sim_focus.scpt, which can only activate the Device Hub app itself.
• Process detection: isSimulatorRunning now matches Device Hub by its executable path, since it hosts all simulators in a single instance and is not necessarily launched with a -CurrentDeviceUDID argument (e.g. when the user opened it manually).

Older Xcodes are unaffected; the legacy spawn path is unchanged and the boot-wait loop is shared.

Note: the devices:// scheme is undocumented — Apple's own Instruments (Devices.xrplugin) uses it internally, and neither simctl nor devicectl offers a public equivalent for showing a device window. If it ever stops working, behavior degrades to a booted simulator without a focused window.

Test

Verified live against Xcode 27 Beta 5 through ioslib.simulator.launch:

• cold launch (Device Hub not running): boots, launches Device Hub, opens + focuses the device window
• killIfRunning: true: running Device Hub is found by path, killed, and relaunched cleanly
• killIfRunning: false with booted device: instance and device reused, window focused
• test-xcode suite passes (4/4); the test-simulator launch tests fail on main too due to hardcoded machine-specific UDIDs

[hansemannn]

@cb1kenobi Tested it already, works great!

[cb1kenobi]

Tested and I agree!