chore(release): bump to v0.31.0

[avrabe]

Summary

Release bump to v0.31.0, shipping the #339 fix merged in #341 (underscore digit-separators inside based numeric literals).

Changes

• [workspace.package] version 0.30.0 → 0.31.0 (Cargo.toml)
• Cargo.lock refreshed via cargo update --workspace --offline
• vscode-spar/package.json version 0.30.0 → 0.31.0
• REQ-PARSER-002 promoted implemented → verified (release v0.31.0); its oracles executed green in fix(parser): accept underscore digit-separators in based literals (#339) #341's required checks

Contents of this release

• Parser: underscore digit-separators rejected inside base-16 literals (16#0800_0000#) but accepted in decimal #339 — parser now accepts _ digit separators inside based literals (16#0800_0000#), consistent with the decimal path.

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Filter: (and (= type "feature") (or (has-tag "v093") (has-tag "v0100")))

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_{Updated automatically by tools/post_verification_comment.py. Source of truth: artifacts/verification.yaml.}