Implement config-driven unlock groups so that multiple things can be unlocked at once (including buildings)

bin/app/data/config/recipes.toml

@@ -142,12 +142,12 @@ duration_seconds = 1.5
 
 # Depth-3 chain (ore -> ingot -> plate -> block) is the factory's
 # doubling-time knob; see the block economy rules in docs/balancing/rules.md.
-# Explicitly unlocked at start (-1): building blocks appear in no
-# schematic's materials, so implicit unlocking can never reach this recipe.
+# unlocked_at_start: building blocks appear in no schematic's materials, so the
+# implicit item graph can never reach this recipe (REQ-LOCK-IMPLICIT).
 [[recipe]]
 id = "building_block"
-unlock_at_station_level = -1
 building = "assembler"
+unlocked_at_start = true
 inputs = [{item = "steel_plate", amount = 2}]
 outputs = [{item = "building_block", amount = 4}]
 duration_seconds = 2.0
@@ -220,15 +220,14 @@ outputs = [{item = "capital_core", amount = 1}]
 duration_seconds = 10.0
 
 # -----------------------------------------------------------------------------
-# Shortcut recipes — drop-only assembler recipe schematics
-# (unlock_at_station_level >= 0). Pure rewards: item threat stays defined by
+# Shortcut recipes — drop-only assembler recipes, gated by unlock groups in
+# unlocks.toml (REQ-LOCK-EXPLICIT). Pure rewards: item threat stays defined by
 # the base (expensive) path via the max rule, so shortcuts give real factory
 # efficiency without shifting any balance.
 # -----------------------------------------------------------------------------
 
 [[recipe]]
 id = "shortcut_steel_plate"
-unlock_at_station_level = 1
 building = "assembler"
 inputs = [{item = "iron_ore", amount = 3}]
 outputs = [{item = "steel_plate", amount = 1}]
@@ -236,7 +235,6 @@ duration_seconds = 2.0
 
 [[recipe]]
 id = "shortcut_control_chip"
-unlock_at_station_level = 2
 building = "assembler"
 inputs = [{item = "quartz", amount = 2}]
 outputs = [{item = "control_chip", amount = 1}]
@@ -244,7 +242,6 @@ duration_seconds = 4.0
 
 [[recipe]]
 id = "shortcut_hardened_steel"
-unlock_at_station_level = 2
 building = "assembler"
 inputs = [{item = "iron_ingot", amount = 4}]
 outputs = [{item = "hardened_steel", amount = 1}]