continue first full balancing round

bin/app/data/config/recipes.toml

@@ -142,8 +142,11 @@ duration_seconds = 1.5
 
 # Depth-3 chain (ore -> ingot -> plate -> block) is the factory's
 # doubling-time knob; see the block economy rules in progression_design.md.
+# Explicitly unlocked at start (-1): building blocks appear in no
+# schematic's materials, so implicit unlocking can never reach this recipe.
 [[recipe]]
 id = "building_block"
+unlock_at_station_level = -1
 building = "assembler"
 inputs = [{item = "steel_plate", amount = 2}]
 outputs = [{item = "building_block", amount = 4}]