Update 20260528

[myfreess]

Changes

This update syncs a batch of MoonBit syntax, lexer, and parser changes, and refreshes the corresponding sync test snapshots.

• Bump the package version from 0.3.2 to 0.3.3.
• Rework source scanning inside string interpolation. The lexer now handles nested {} inside interpolation expressions, string/char/byte-string/regex-string atoms, and reports clearer lexical errors for unsupported interpolation contents such as comments, multiline strings, and attributes.
• Update both the yacc parser and the handrolled parser:
  • Trait method declarations now support a fn header with optional type parameters.
  • impl ... with method definitions now accept an optional fn prefix.
  • <+ template writing is parsed as a postfix expression instead of being limited to left-values in statement parsing. The RHS handling is unified for normal strings, interpolated strings, and multiline string templates.
• Regenerate yacc_parser/parser.mbt and yacc_parser/parser.mbt.map.json.
• Refresh sync tests and snapshots. This adds/enables coverage for cases such as bytes_range_equal, utf_conversion, try_expr_catch_bang, postfix_catch_all, string_interp_boundary_scanning, string_or_pattern_fastpath, and templated_writing_lambda, while removing or replacing a batch of older pipeline snapshots.