The function multiplied monthly_bytes (in bytes) by cost_per_gb as a
raw number, producing a result ~1e9x too large (e.g., $1.87T instead
of $233 for 1 MB/s at $0.09/GB). The fix converts cost_per_gb to
dollar/byte before multiplying so units cancel correctly.
Also adds tests for calc_monthly_egress_cost, calc_fleet_tco, and
calc_mtbf_node, which had no test coverage.
Align the MLSys·im code, docs, paper, website, workflows, and lab wheel for the 0.1.1 release. This also fixes runtime/API issues found during release review and prepares the paper PDF plus archive package.