Feature request: Convert long repeated strings to `.repeat()` when minifying

**Is your feature request related to a problem? Please describe.**
Whenever I minify long strings using this minifier, The strings are left untouched. It would be nice if the long strings (Example `'░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░'`) could be changed to `'░'.repeat(35)`, which saves 21 characters

**Describe the solution you'd like**
Replace long enough strings with `.repeat()` when minifying

**Describe alternatives you've considered**
We could do this in the source code itself, but that defeats the purpose of a minifer

**Additional context**
NA

The issue names no files or tests. Start by locating the JavaScript minifier's handling of string literals and its existing regression tests; clarify the length threshold and compatibility constraints before proceeding. Done means eligible repeated strings are converted to equivalent `.repeat()` expressions with tests covering the requested example and unchanged behavior for other strings.

Written by the indexing model from the issue text.