feat(metrics): add metrics collection system, exclude output from git

- Add comprehensive metrics scripts
- Track scripts but exclude metrics_out/ directory
- GitHub, CI, compression benchmarks
- Timestamped aggregate reports

Author: 29deepanshutyagi

.gitignore

@@ -33,3 +33,6 @@ scripts/*
 !scripts/metrics/
 !scripts/metrics/*.sh
 metrics_out/
+
+# Metrics output directory
+metrics_out/