fix(benchmarks): strip block comments before counting LOC

[Lakshya77089]

Fixes #231.

loc.js filtered comments line by line, so /* ... */ block comments whose continuation lines are not *-aligned had their inner lines counted as code. A plain indented block comment scored higher than the same code written JSDoc-style:

function f() {        function f() {
  /* explain             /*
     the rest */          * explain
  return 1;               */
}                       return 1;
                      }
scores 5                scores 3   <- same code, different count

This strips /* ... */ before the line count so both forms agree, and adds benchmarks/loc.test.js to lock it.

Why it matters: the over-count lands on whichever arm writes more block comments, which is the verbose baseline more often than ponytail, so it nudged the headline "less code" number in ponytail's favor. Small, but worth keeping honest.

Verified:

• indented and JSDoc block comments now both count 3
• inline /* */, //, and # line comments still handled
• plain code is unchanged

node benchmarks/loc.test.js passes (5/5); the main test suite is unaffected.