we (web engine): Experimental web browser project to understand the limits of Claude

Add Makefile and implementor logging/rate-limit wiring master

- Makefile default target runs build.sh - implementor mirrors stdout/stderr to implementor.log - implementor reads per-runner per-window caps from implementor-rate-limits.json each iteration; pauses when both runners are over cap - gitignore implementor.log and implementor-rate-limits.json Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>