chore(apple/M1): move widget sources into the Xcode target's synced folder

Xcode created the PunktfunkWidgetsExtension target with a file-system-
synchronized root group at clients/apple/PunktfunkWidgets/, so the target
compiles whatever lives there. Deleted the three generated stubs
(PunktfunkWidgets.swift / PunktfunkWidgetsBundle.swift /
PunktfunkWidgetsControl.swift — the stub @main WidgetBundle would collide with
ours) and moved our sources (PunktfunkWidgetBundle / HostsWidget /
SessionLiveActivity) from Sources/PunktfunkWidgets/ into PunktfunkWidgets/. Kept
the generated Info.plist (build-excluded via the sync exception set) and
Assets.xcassets. Still outside Sources/, so SwiftPM ignores it; swift build green.

project.pbxproj is intentionally NOT part of this commit — the target's
capability/signing edits (step 3) are still in progress in Xcode.

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

clients/apple/PunktfunkWidgets/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -0,0 +1,35 @@
+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "tinted"
+        }
+      ],
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}