Enable variable-length messages up to 32 KiB.

Enable variable-length messages up to 32 KiB.

Add dedicated buffer for sign/verify message data and refactor references to use length variables. Convert terminology from "block hash" to "message" to reflect new capabilities and document how Nano block hashes should be handled. Deprecate crypto_hash and instead use blake2b directly for streaming hash updates. Update test webpage and NodeJS test to use full set of test vectors from the Python ed25519-blake2b library. Update workers to transfer bytes instead of copying them, and always specify worker commands with the 'action' property.