Fix ThreatCostCalculator: per-unit division, scrap fallback, fixpoint, staggered-recipe max

tools/threat_report.py

@@ -23,10 +23,11 @@ Reads recipes.toml, ships.toml, modules.toml, and world.toml and prints:
   5. Belt feasibility — input demand in items/s per building vs. the
      single-belt cap (belt_speed_mps / tile_size_m, in items/s).
 
-NOTE: the per-unit division (1) and the scrap fallback rule are the
-agreed design semantics (see docs/progression_design.md action items);
-src/lib/sim/ThreatCostCalculator.cpp does not implement them yet. Until
-it does, this report is the design reference, not a mirror of the game.
+NOTE: the semantics described above — per-unit division, scrap fallback
+rule, fixpoint resolution including reprocessing, and the commit-all-
+recipes max rule — are implemented in both this script and in
+src/lib/sim/ThreatCostCalculator.cpp. The two should produce identical
+values for any given config.
 
 Usage (from the repository root or anywhere else):