v0.3.5

SIMD optimizations: digit scanning, bulk string copy, escape mode tuning

- Add skip_ascii_digits() with to_bitmask precision for number parsing
- Add bulk copy in decode_escaped_string via find_escape_json
- Switch find_escape_html/unicode/javascript to .any()+break pattern
- Add skip_whitespace() with to_bitmask precision
- Add SIMD boundary tests (27 tests targeting handrolled logic)
- Document optimization history to prevent regression re-attempts
- Update RELEASE.md asset count from 30 to 45

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>