Add Stateful Programmable Switch accessory

[yfre]

Closes #161

What

Adds support for the Stateful Programmable Switch service:

New class	HAP	Details
StatefulProgrammableSwitchAccessory	accessory interface	switch event (read, events), output state (read, write, events); default getServices()
StatefulProgrammableSwitchService	service 00000088	required: Programmable Switch Event (73), Programmable Switch Output State (74); optional: Name (if the accessory implements AccessoryWithName)
ProgrammableSwitchOutputStateCharacteristic	characteristic 00000074	uint8, 0–1, step 1, perms pr/pw/ev

This service isn't in Apple's public HAP specification or the HomeKit ADK. The definitions follow HAP-NodeJS, as the issue suggests. ProgrammableSwitchOutputStateCharacteristic uses the IntegerCharacteristic format constructor from #203 to advertise uint8.

Compatibility

Purely additive: three new classes and no changes to existing classes. Behavior is unchanged for existing accessories, including openHAB setups.

Caveat

Reports from the homebridge community suggest the Apple Home app doesn't display stateful programmable switches; third-party HomeKit apps can use them. I haven't verified this on a device. Library users get the API either way, but end users may only see it in third-party apps.

Testing

mvn -B package on JDK 11: all 28 tests pass. The new StatefulProgrammableSwitchServiceTest covers:

• service type 88 and the required characteristic order (73, 74), plus Name when AccessoryWithName is implemented
• the default getServices() returning the stateful switch service
• output state JSON: uint8, pr/pw/ev, min 0, max 1, minStep 1, no unit
• writes reaching setSwitchOutputState, and subscribe/unsubscribe delegation
• the switch event staying read-only with events

🤖 Generated with Claude Code

[ccutrer]

I'll admit I'm still cloudy on how this is even intended to be used. At the least I'd like to see a comment linking to https://developer.apple.com/documentation/homekit/hmservicetypestatefulprogrammableswitch showing it's a real thing, even if it is poorly documented.

[yfre]

@ccutrer i was also thinking about it yesterday. i tend to drop this PR as there is not use for it. i just had on the list of accessories which HAP supports.. but again, unclear how to use it.

i will drop this PR.
thank you for the review, two other PRs should be more useful :)