Update test vectors for ERC-4361 erratum

[jwahdatehagh]

Summary

Updates the canonical SIWE test vectors for the surviving behavior changes in signinwithethereum/ERCs#1.

Changes:

• Reclassifies two userinfo@ domain vectors from positive to negative, matching the ERC-4361 erratum's exclusion of the RFC 3986 userinfo subcomponent from SIWE domain values.
• Updates statement character vectors for the printable-ASCII widening: printable ASCII punctuation is now valid for statement, while LF and other controls remain excluded.

Vectors moved from vectors/parsing/parsing_positive.json to vectors/parsing/parsing_negative.json:

• domain is RFC 3986 authority with userinfo (test@127.0.0.1)
• domain is RFC 3986 authority with userinfo and port (test@127.0.0.1:8080)

Statement vector changes:

• vectors/grammar/valid_chars.json now treats full printable ASCII (0x20 through 0x7E) as valid for statement.
• Obsolete negative statement punctuation cases were removed from vectors/grammar/invalid_chars.json.

Coordination

This PR is held open pending resolution of the ERC-4361 erratum. Downstream SIWE libraries should consume this vector update when they implement the surviving parser changes: reject userinfo@ in domain and accept the widened statement character set.

Evidence

See the erratum evidence repository:

• Findings catalogue: https://github.com/signinwithethereum/erc-4361-erratum/blob/main/inconsistencies.md
• Conformance matrix: https://github.com/signinwithethereum/erc-4361-erratum/blob/main/conformance-matrix.md
• Proposed diffs: https://github.com/signinwithethereum/erc-4361-erratum/blob/main/proposed-diffs.md