v0.2.1-alpha

Changed

• Removed the two deprecated syntax forms (spec v2.3): the |> pipeline operator is now a parse error E0010 (use class methods/direct calls instead), and newline-separated statements are now a parse error E0011 (; is the sole statement separator; a statement not followed by ; before end-of-input or a block-closing } is rejected). The W0001/W0002 warning codes and the parser's pending_newline machinery were deleted; the ExprKind::Pipeline/BinOp::Pipeline AST variants and the evaluator's pipeline lowering were removed.
• Completed the English translation of the language docs: docs/SPECIFICATIONS-en_US.md and docs/IMPLEMENTATION-en_US.md no longer contain untranslated Chinese (code comments, diagrams, and labels are now in English; the bilingual Glossary table is retained).