fix(rpc): support Accept parameters and media ranges

[huklaa]

Fixes #341.

Summary

• parse comma-separated "Accept" media ranges instead of treating the whole header as one media type
• ignore supported ranges with "q=0"
• keep "application/json" and "/" as default-version fallbacks
• add regression coverage for parameters, multiple ranges, zero quality, malformed quality values, and unsupported versions

Testing

Focused parser regression tests were added under "crates/malachite-app/src/rpc/version.rs".