v0.2.0 — Automatic WASM64 runtime for large feeds

GTFS Analyzer v0.2.0 introduces automatic dual-runtime selection. Browsers with WebAssembly Memory64 support use the WASM64 serial engine, allowing feeds that exceed the wasm32 4 GB linear-memory ceiling to be analyzed directly in the browser. Other browsers automatically fall back to WASM32 threaded or serial mode.\n\nHighlights:\n- Automatic WASM64-first runtime selection with safe WASM32 fallback\n- Active engine indicator in the upload interface and diagnostic exports\n- URL overrides for WASM32, WASM64, and serial diagnostics\n- CI builds and validates all three runtime packages\n- Deterministic wasm32/wasm64 Golden output parity check\n- Verified 250 MB feed with 34.5 million stop_times at approximately 5.3 GB memory\n\nAll Rust tests, TypeScript tests, security checks, production builds, output-parity checks, and Playwright E2E tests passed.