Sync parser_test.zig test section with upstream, adding ~40 new tests
(testError, testCanonical, testTransform). Remove extra blank lines
between tests to match upstream formatting.
Fix tokenizer keyword lookup bug: getKeyword() returned TOKEN_INVALID
when input was longer than a keyword prefix (e.g., "orelse" matched
"or" prefix then bailed out instead of continuing to find "orelse").
Fix parser to handle if/for/while expressions in type position (e.g.,
function return types like `fn foo() if (cond) i32 else void`). Add
labeled block support in parsePrimaryTypeExpr. Replace assert for
chained comparison operators with longjmp error.
365/381 tests pass. Remaining 16 failures are parser limitations for
specific syntax patterns and error recovery.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
