betto_icu

Initial release.

Added

• Tokenizer — abstract interface for text segmentation. Implementations return only word-like tokens (letters and digits); punctuation and whitespace are discarded.

• IcuTokenizer — UAX #29 word-boundary segmentation via the system ICU library (FFI). Handles non-Latin scripts: CJK, Arabic, Thai, Devanagari, and more. Supported platforms:

  Platform	Library
  macOS / iOS	libicucore.dylib (ships with the OS)
  Android	libicuuc.so (NDK)
  Linux	libicuuc.so.NN (install libicu-dev/icu)
  Windows	icu.dll (Windows 10+)

  Probes for ICU symbol renaming (e.g. ubrk_open_76 on Debian Trixie+ and Fedora) so no manual configuration is needed.

  Uses RegExp-based span classification instead of ubrk_getRuleStatus() for portability across all supported platforms, including Apple's libicucore which does not export UAX #29 rule-status tags.

• RegExpTokenizer — pure-Dart tokenizer using RegExp with Unicode property escapes (\p{L}, \p{N}). Zero FFI dependencies; suitable for English prose and common technical identifiers (mTLS, 0x8004210B, etc.). Works on every platform, including web.

• BrowserTokenizer — UAX #29 word-boundary segmentation via the browser's Intl.Segmenter API (dart:js_interop). Web-only; zero bundle cost. Requires Chrome 87+, Firefox 125+, or Safari 16.4+. On native targets the conditional import resolves to a stub that throws UnsupportedError.

• Conditional export pattern in lib/betto_icu.dart: the correct IcuTokenizer implementation (real FFI or stub) and BrowserTokenizer implementation (real JS interop or stub) are selected at compile time via dart.library.ffi and dart.library.js_interop.

• IcuTokenizer.forPlatform(String platform) — named constructor that loads the ICU library for an explicit platform string. Enables tests to exercise each library-loading branch without requiring the native OS.

• bin/tokenize.dart — command-line tool that tokenizes a string with either or both tokenizers (--icu, --regexp).

• Flutter integration test app (integration_test_app/) — runs the full contract and UAX #29 test suite on Android and iOS via package:integration_test.