Block Runner 0.9.8

Block Runner 0.9.8 fixes dependency compatibility when installing into an existing WordPress project.

• Allow newer compatible versions of the six optional proof-tool dependencies without forcing npm peer-dependency overrides.
• Update the pinned Gutenberg packages together, fixing the reported author() crash in projects using @wordpress/blocks 16.0.0.
• Improve the README, architecture and command reference, with a runnable custom conversion rule example.

The proof command still requires its exact tested toolchain; the wider peer ranges allow other project tooling to coexist during installation.

Thanks @mattheu for tracking down the compatibility issues and testing the fix in a real project in #116.

Full changelog: v0.9.7...v0.9.8