feat: add engine comparison benchmark and fix Flare package name (#307)

- Add examples/benchmark/ with a standalone HTML demo that benchmarks
  MLC (WebGPU), Transformers.js (ONNX/WASM), and Flare (GGUF/WASM)
  engines side-by-side on the same model and prompt. Measures model load
  time, TTFT, and tokens/sec with configurable runs and warmup.
- Rename @aspect/flare to @sauravpanda/flare throughout the codebase —
  the package is published on npm as @sauravpanda/flare@0.2.0, not under
  the @aspect scope.

Closes #299

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: sauravpanda