[LSP] Fix ParseError enum variants

## Problem
The LSP references `ParseError` variants that don't exist.

## Files Affected
- `tools/lsp/src/main.rs`

## Missing Variants:
- `ParseError::UnterminatedString` 
- `ParseError::InvalidNumber`

## Fix
These need to be replaced with valid `ParseError` variants or removed. Check the actual `ParseError` enum definition.

## Priority
Medium

## Labels
- lsp