feat: UxUrl — native URL / phone / email detection + tap launcher

Sync FFI from Dart into platform detectors:
- iOS / macOS: NSDataDetector(.link | .phoneNumber) + a tight bare-domain
  pass that requires `/` or `?` (so `etc.` / `v1.2.3` don't false-positive
  while `example.com/path` does match). NFKD-fold the phone capture so
  full-width / Arabic-Indic digits collapse to ASCII; stop the digit run
  at the first letter so `+1 555 1234 ext.99` doesn't fuse the extension.
- Android: JNI into android.util.Patterns (WEB_URL / EMAIL_ADDRESS / PHONE)
  via a cached JavaVM, std::call_once for init, full per-call
  ExceptionCheck coverage. UTF-16→UTF-8 conversion is hand-rolled to dodge
  the Modified-UTF-8 / CESU-8 incompatibility with Dart's utf8.decode.

`UxUrl.launch(url)` is the matching tap action. Channel side dispatches via
UIApplication / NSWorkspace / Intent.ACTION_VIEW. Dart-side gates the URL
against a scheme allowlist (http, https, mailto, tel, sms, banlu, tg),
rejects bidi-override controls (U+202A..E / U+2066..9) to prevent visual
spoofs, and blocks USSD / MMI tel: codes containing `*` or `#`.

Library/native cleanup along the way:
- Renamed libux_keyboard.so to libux.so (also covers sensor + url).
- Collapsed three near-identical FFI loader stanzas across keyboard / sensor
  / url into a shared lib/src/_ffi.dart with `uxLib` + typed `uxLookupX`
  helpers.

macos/ux.podspec

@@ -27,7 +27,7 @@ mkdir -p "$DEST"
 rsync -a --delete "$SRC/" "$DEST/"
 CMD
   }]
-  s.source_files     = 'Classes/**/*.swift'
+  s.source_files     = 'Classes/**/*.{swift,m}'
   s.frameworks       = ['AVFoundation', 'CoreMedia', 'CoreVideo']
   s.dependency 'FlutterMacOS'
   s.osx.deployment_target = '10.15'