v0.8.18

• Updated the default llama.cpp native runtime pin to
  leehack/llamadart-native@b10276, picking up Qwen3-TTS model-loading
  primitives, explicit bundled-MTP loading, automatic model-specific token
  suppression, and recent model, multimodal, speculative-decoding, backend,
  and runtime fixes. Regenerated matching Dart FFI bindings, migrated model
  loading to llama.cpp's load-mode ABI and the penalty sampler to the new
  vocabulary-sized ABI, and refreshed the llamadart_llama_cpp_flutter Apple
  SwiftPM checksum. Speech generation is not yet exposed through the public
  Dart API.

• Updated the default LiteRT-LM runtimes to
  leehack/litert-lm-native@v0.15.0-native.3 and
  @litert-lm/core@0.15.0. The native artifact includes a corrected v0.15
  streaming callback bridge and an Android Dawn rollback for Mali-G715 GPU
  device loss; incompatible callback runtimes now fail safely before
  generation, and concrete macOS app, framework, and cache libraries take
  precedence over process-linked assets.

• Disabled automatic WebGPU fetch-backed model loading by default. Streamed
  loading remains the safe default; controlled range-capable deployments can
  opt in explicitly.

• Updated WebGPU bridge assets to v0.1.26 (llama.cpp b10276), refreshing
  both WebAssembly runtimes while preserving the existing bridge API.