Optimize F# Type-check Graph

Make the compiler's conservative file-dependency graph smaller and shallower. Do not treat a simpler graph as proof of a faster build. Prove measurement, dependency structure, and compatibility separately.

1. Fix the measurement contract

Record the project, SDK, compiler version, configuration, target framework, and build command. Record the machine conditions and build state. Time the compiler phase and each file activity. Also time the complete build. Define the run count, warm-up policy, and minimum useful improvement.

Use repeated runs and compare medians. Keep the raw reports. Keep the workload, flags, and cleanup procedure identical for both cases.

Complete this step when another person can reproduce the baseline. The baseline must identify the dominant compiler activities.