Refactored the autocomplete variable matching logic in `src/ui/editor.ts` to iterate through document lines using CodeMirror's `iterLines()` instead of allocating the entire document string in memory with `toString()`. Also pulled the regex up and introduced a quick `.includes("=")` bailout to skip the regex engine completely for most lines.
Co-authored-by: Horizontal42 <75383519+Horizontal42@users.noreply.github.com>
