Add first numbers pass for the v2 production tree

content_design.md: full recipe quantities and durations computed with
a recursive threat calculator - economy constants (scrap_per_threat
0.25, reprocessing 4 scrap / 4 s, voidsteel at threat 100), per-item
threat values, module contributions, and fitted ship threats vs the
ladder (96-124%, smooth ~x2-per-class curve). Checks recorded: ratio
curve realized (t1 1:1, t2 2:3, t3 strange), belt feasibility under
the single-belt cap, block at 4 threat implying ~18 blocks average
building cost for the 4-minute doubling target, and a small-end
deviation note recommending ladder adjustment over chain thinning.

progression_design.md: two new action items - amend REQ-THREAT-ITEM to
exclude scrap-consuming recipes from item threat (the max rule would
otherwise inflate basic materials via the scrap smelting recipe), and
port the calculator to tools/threat_report.py.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DyCu8vwChKMbLJQ3xosYEN

docs/progression_design.md

@@ -373,3 +373,16 @@ in `requirements.md` and the git history). Still open:
    one matching deposit tile). Touches REQ-BLD-MINER ("every asteroid
    tile is equivalent" no longer holds), REQ-GW-ASTEROID-EXPAND /
    REQ-EXP-*, `world.toml`, and `visuals.toml`.
+6. **Exclude scrap-consuming recipes from item threat.** Amend
+   REQ-THREAT-ITEM: recipes that take scrap as an input do not
+   participate in an item's threat computation (neither as its value
+   nor in the max-across-recipes rule). Otherwise the scrap→ingot
+   smelter recipe inflates the basic materials' threat via the max
+   rule, poisoning every downstream value. Scrap conversion is already
+   accounted for by the REQ-THREAT-SCRAP constant.
+7. **Threat report tool.** Port the numbers-pass calculator to
+   `tools/threat_report.py`: per-item threat values, module
+   contributions, fitted ship threats vs. the ladder targets,
+   producer:consumer ratio tables, and belt-feasibility checks, read
+   from the real config files. Re-run after any recipe or material change, like
+   `verify_recipes.py`.