fix(#323): widen parser-error range to offending token length

[kreinba]

This addresses #323. The diagnostics loop in validateTextDocument built a Range whose end matched start, which produced zero-length squiggles that VSCode renders as an invisible caret and that some other LSP clients drop entirely.

The fix derives the offending token's length inside ErrorListener.syntaxError from the ANTLR symbol when one is supplied, falls back to one character when ANTLR omits the symbol, and threads that length through ParserError so the diagnostic Range ends at column + length. Clients now paint a real squiggle on every parser error instead of a hidden caret.

make runs end to end on the branch: parser generation, tsc -b, ncc bundle, 40 jest tests at 100 percent statement and 100 percent branch coverage on errorListener.ts, and eslint src --ext .ts clean. A new test in test/parser.test.ts pins that every ParserError carries a length of at least one, and a unit test exercises the symbol === undefined fallback path.

Closes #323

[kreinba]

make (22.x) is red on the same Eo.g4 404 that blocks every other open PR (issue #352, fix in #367). The other eight workflows are green and the diff is independent of the grammar vendoring, so this should turn green automatically once #367 lands.

[Thayorns]

@yegor256 This PR can be merged once build is up