feat(apple/M1+M3+M4): widgets, Live Activity, and Siri/Shortcuts intents

The extension-side + App Intents surface for design/apple-live-activities-and-
widgets.md. The iOS-framework code (WidgetKit/ActivityKit/AppIntents) can't be
compiled by the macOS `swift build` CI target and needs the Xcode widget-
extension target that only exists once created in the GUI — see the checklist in
the memory note. What macOS DID verify: HostEntity (AppIntents is available on
macOS), the shared attribute/notification plumbing, and that nothing regressed
(142 tests green).

Shared (PunktfunkShared):
- PunktfunkSessionAttributes (ActivityAttributes) — the one type app + extension
  share; gated os(iOS) (ActivityKit imports on macOS but its types are
  unavailable, so canImport would wrongly admit it).
- EndStreamIntent (LiveActivityIntent) — posts .punktfunkEndActiveSession.
- HostEntity + HostEntityQuery (AppEntity over the shared store) — the intent /
  widget-config parameter type; canImport(AppIntents), so macOS type-checks it.
- New notifications: end-active-session, open-deep-link.

M1 widget extension sources (Sources/PunktfunkWidgets/, NOT a SwiftPM target —
`swift build` ignores the dir):
- PunktfunkWidgetBundle (@main): HostsWidget + PunktfunkSessionLiveActivity.
- HostsWidget (kind "PunktfunkHosts"): reads the shared-suite store, sorts by
  recency, deep-links each host; small/medium/accessory families; empty state.
- SessionLiveActivity: Lock-Screen banner + Dynamic Island (elapsed timer,
  mode line, background countdown, End button).

M3 controller (app, iOS): SessionActivityController owns the Activity lifecycle
(request/update/end + launch orphan-sweep + staleDate); ContentView drives it
from the model's phase/isBackgrounded/backgroundDeadline (which SessionModel now
publishes), keeping ActivityKit out of the cross-platform model.

M4 (app, iOS): ConnectToHost/WakeHost intents + AppShortcutsProvider; Connect
routes via .punktfunkOpenDeepLink into the same onOpenURL router (one set of
guards); Wake reuses the WoL path; End surfaced to Shortcuts too.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/apple/Sources/PunktfunkShared/DefaultsKeys.swift

@@ -131,4 +131,15 @@ extension Notification.Name {
     /// menus) — it exists so the menu item is honest whenever it CAN fire, and as the shortcut's
     /// discoverable menu-bar surface.
     public static let punktfunkReleaseCapture = Notification.Name("io.unom.punktfunk.release-capture")
+
+    /// Posted by the Live Activity's / Shortcuts' End-stream intent (`EndStreamIntent.perform`,
+    /// which runs in the app's process): the app tears the active session down deliberately
+    /// (quit-close the host). Same cross-process-signal pattern as `punktfunkReleaseCapture` —
+    /// the intent lives in PunktfunkShared and can't reach the app's `SessionModel` directly.
+    public static let punktfunkEndActiveSession = Notification.Name("io.unom.punktfunk.end-active-session")
+
+    /// Posted by the Connect App Intent (Siri/Shortcuts) with a `punktfunk://` URL as `object`:
+    /// the app routes it through the SAME `.onOpenURL` handler a widget tap uses (one router, one
+    /// set of guards). The intent uses `openAppWhenRun`, so the app is foregrounded to receive it.
+    public static let punktfunkOpenDeepLink = Notification.Name("io.unom.punktfunk.open-deep-link")
 }