add iron/gold smelting + disambiguate workbench-vs-recipe

Q: iron_smelt (iron_ore + wood → iron_ingot) and gold_smelt
(gold + wood → gold_ingot) recipes added at Smelter, using the
existing ingredient2 buffer mechanism. New TYPE_IRON_INGOT and
TYPE_GOLD_INGOT item types (procedural hue-hash draw for now).

R: new Recipe.target_workbench field (StringName, empty = any matching
skill) round-trips through to_dict/from_dict. Workbench bill picker
filters by both required_skill AND target_workbench vs lower-cased
label_text. plank → carpenter, stone_block/iron_smelt/gold_smelt →
smelter, flour → millstone. Cooking-only recipes (bread, meal) stay
unrestricted since Hearth is the only cooking workbench.

9 recipes total now, 4 distinct workbench routes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scenes/ai/recipe.gd

@@ -46,6 +46,13 @@ var skill_threshold: int = 0
 ## call Strings.t("item." + id) for player-visible text.
 var label: String = ""
 
+## Optional workbench affinity. When non-empty, the bill picker only shows this
+## recipe at workbenches whose label_text.to_lower() matches this value.
+## Empty string (default) means "any workbench whose accepted_skill matches" —
+## i.e. the pre-Phase-19 behaviour and the correct fallback for older saves.
+## Values should be lowercase: &"carpenter", &"smelter", &"millstone".
+var target_workbench: StringName = &""
+
 
 # ── save / load ───────────────────────────────────────────────────────────────
 
@@ -70,6 +77,7 @@ func to_dict() -> Dictionary:
 		"required_skill": String(required_skill),
 		"skill_threshold": skill_threshold,
 		"label": label,
+		"target_workbench": String(target_workbench),
 	}
 
 
@@ -85,4 +93,7 @@ static func from_dict(d: Dictionary) -> Recipe:
 	r.required_skill = StringName(d.get("required_skill", str(SKILL_CRAFTING)))
 	r.skill_threshold = int(d.get("skill_threshold", 0))
 	r.label = str(d.get("label", ""))
+	# Default to empty — old saves without this key get the pre-Phase-19
+	# "any matching skill" behaviour, which is correct.
+	r.target_workbench = StringName(d.get("target_workbench", ""))
 	return r

scenes/ai/recipe_catalog.gd

@@ -23,6 +23,7 @@ static func plank() -> Recipe:
 	r.work_ticks = 60        # ~3 sim seconds at 1×  (20 Hz × 3 s = 60 ticks)
 	r.required_skill = Recipe.SKILL_CRAFTING
 	r.skill_threshold = 0
+	r.target_workbench = &"carpenter"
 	return r
 
 
@@ -35,6 +36,7 @@ static func stone_block() -> Recipe:
 	r.work_ticks = 80        # ~4 sim seconds at 1×
 	r.required_skill = Recipe.SKILL_CRAFTING
 	r.skill_threshold = 0
+	r.target_workbench = &"smelter"
 	return r
 
 
@@ -52,6 +54,7 @@ static func flour() -> Recipe:
 	r.work_ticks = 50        # ~2.5 sim seconds at 1× — quick grinding pass
 	r.required_skill = Recipe.SKILL_CRAFTING
 	r.skill_threshold = 0
+	r.target_workbench = &"millstone"
 	return r
 
 
@@ -125,9 +128,46 @@ static func quarry_stone() -> Recipe:
 	return r
 
 
+# ── Phase 19 — iron/gold smelting ────────────────────────────────────────────
+
+static func iron_smelt() -> Recipe:
+	## Iron ore → iron ingot. Worked at the Smelter (accepted_skill = crafting).
+	## Secondary fuel ingredient (wood) is recorded but not yet enforced at
+	## runtime — CraftingProvider only checks the primary ingredient today.
+	var r := Recipe.new()
+	r.id = &"iron_smelt"
+	r.label = "Smelt iron ingot"
+	r.ingredient_type = Item.TYPE_IRON_ORE
+	r.ingredient2_type = Item.TYPE_WOOD
+	r.ingredient2_count = 1
+	r.output_type = Item.TYPE_IRON_INGOT
+	r.work_ticks = 200       # ~10 sim seconds at 1× — slower than stone-block
+	r.required_skill = Recipe.SKILL_CRAFTING
+	r.skill_threshold = 0
+	r.target_workbench = &"smelter"
+	return r
+
+
+static func gold_smelt() -> Recipe:
+	## Gold ore → gold ingot. Same smelting chain as iron.
+	var r := Recipe.new()
+	r.id = &"gold_smelt"
+	r.label = "Smelt gold ingot"
+	r.ingredient_type = Item.TYPE_GOLD
+	r.ingredient2_type = Item.TYPE_WOOD
+	r.ingredient2_count = 1
+	r.output_type = Item.TYPE_GOLD_INGOT
+	r.work_ticks = 200       # ~10 sim seconds at 1×
+	r.required_skill = Recipe.SKILL_CRAFTING
+	r.skill_threshold = 0
+	r.target_workbench = &"smelter"
+	return r
+
+
 ## Returns one fresh instance of every recipe in the catalog. Used by UI
 ## recipe-pickers to enumerate available bills; callers filter by
-## `recipe.required_skill` against the workbench's `accepted_skill`.
+## `recipe.required_skill` and `recipe.target_workbench` against the
+## workbench's `accepted_skill` and `label_text`.
 static func all() -> Array[Recipe]:
 	return [
 		plank(),
@@ -137,4 +177,6 @@ static func all() -> Array[Recipe]:
 		meal_from_vegetables(),
 		cremate_corpse(),
 		quarry_stone(),
+		iron_smelt(),
+		gold_smelt(),
 	]