Fix iOS app build

[colemancda]

Follow-up to #22: gets the iOS app building and running from a clean checkout with no
workarounds — no SwiftPM mirrors, no environment variables, no extra xcodebuild flags, and no
edits needed before pressing Run in Xcode.

Verified end to end: a clean swift build, swift test (44 pass), xcodebuild build,
xcodebuild archive, and the app launched in the simulator — the device list populates from
MockCentral, and all 13 bundled plugins install into Documents/Plugins/ on first launch and
appear in the Plugins tab.

Five fixes

1. Two regressions I introduced when removing Skip in #22, neither caught by swift build:

• Darwin/BluetoothExplorer.xcconfig still #included the deleted Skip.env, so PRODUCT_NAME
  was empty and archiving failed with "Multiple commands produce .app". App identity (name,
  bundle id, version) is now declared in the xcconfig directly.
• The Xcode project still ran Skip's "Run skip gradle" build phase. It had been suppressed by
  SKIP_ACTION = none, which I removed along with the rest of the Skip config — so simulator
  builds started shelling out to gradle and failing on the missing Skip.env. The phase is gone.

Both only appear through Xcode, which is why swift build passing in #22 did not catch them.

2. AndroidBluetooth is temporarily not declared. SwiftPM validates the whole package graph
even for .android-conditional dependencies, so its AndroidManifest bug (PureSwift/Android#40
moved that product to swift-android-native) broke Apple builds — a clean checkout could not
build at all without a local mirror. The Swift sources already guard their use with
#if os(Android), so nothing else changed. Restore it alongside PureSwift/AndroidBluetooth#4.

3. WasmKit now comes from a fork (MillerTechnologyPeru/WasmKit, one commit) that drops
.treatAllWarnings(as: .error). Upstream's setting collides with the -suppress-warnings Xcode
passes to package dependencies:

error: Conflicting options '-warnings-as-errors' and '-suppress-warnings' (in target 'WasmTypes')

I confirmed the override only reaches package targets from the command line — setting it in the
xcconfig or at project level does nothing — so opening the project in Xcode and pressing Run
failed, and only a patched WasmKit fixes that. Worth upstreaming; a package arguably should not
impose its warning policy on consumers.

4. CI is simplified accordingly. With the fork in place the SWIFT_SUPPRESS_WARNINGS=NO
workaround is gone, and the Android job is dropped since the app no longer declares
AndroidBluetooth. Two jobs remain: Test, and iOS Archive, which asserts the archive
contains BluetoothExplorer.app with bundled .wasm plugins and uploads it as an artifact.

Reviewer notes

• Android is deliberately parked. Documentation/AndroidSwiftUIMigration.md records what is needed
  to bring it back: the two PureSwift dependency PRs, an upstream fix for AndroidBluetooth's
  @JavaImplementation macro generating invalid code for swiftOnScanFailed(error:), and a
  replacement for Skip's gradle project.
• The WasmKit fork is pinned by revision, so it cannot drift. Drop it once upstream fixes the
  setting.