Increase iteration counts for small/medium benchmarks

Small: 1000→2000, medium: 200→500. The previous run showed gts small
still drifting at -3.4% while medium/large were within 1%. More
iterations per sample further dilutes GC and scheduling noise.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

Author: NullVoxPopuli

tests/parser.bench.mjs

@@ -114,7 +114,7 @@ globalThis.gc?.();
 // More iterations per sample → individual GC spikes get diluted, reducing
 // variance on noisy CI runners.  Scale down for larger fixtures so each
 // sample doesn't take too long (mitata needs many samples for stable stats).
-const BENCH_ITERS = { small: 1000, medium: 200, large: 100 };
+const BENCH_ITERS = { small: 2000, medium: 500, large: 100 };
 
 for (const { type, ext, experimentParse, controlParse } of PARSERS) {
   for (const size of SIZES) {