Add Go, Python, and C-header inbound-frontier fixtures to scripts/benchmark-incremental-speed.py with an explicit --frontier-files denominator and single-definition mutations.
Teach build_index_result() to accept peak_mb from mem.phase, pipeline.done, or incremental.done. Emit terminal RSS fields from cbm_pipeline_run() and log_incremental_done() only while cbm_profile_active is true, preserving normal-run logging and avoiding memory queries outside experiment mode.
Validated with the -O2 CLI matrix (3/3 canonical graph gates, cleanup=true, peak RSS present on initial/incremental/fresh routes), the ASan+UBSan C runner (375 passed), benchmark Python tests (35 passed, 5 subtests), and Ruff.
Signed-off-by: Andrew Hundt <ATHundt@gmail.com>