feat(core): declare crafting recipe matching interface

core/include/vf/Crafting.h

@@ -0,0 +1,101 @@
+#pragma once
+
+#include <array>
+#include <vector>
+#include "Item.h"
+
+namespace vf {
+
+constexpr int craftGridWidth = 3;
+constexpr int craftGridHeight = 3;
+constexpr int craftGridCells = craftGridWidth * craftGridHeight;
+
+using CraftGrid = std::array<ItemId, craftGridCells>;
+
+struct CraftResult {
+    ItemId item = ItemId::None;
+    int count = 0;
+
+    bool valid() const { return item != ItemId::None && count > 0; }
+};
+
+struct ShapedRecipe {
+    int width = 0;
+    int height = 0;
+    std::array<ItemId, craftGridCells> pattern{};
+    CraftResult result;
+    bool allowMirror = true;
+};
+
+struct ShapelessRecipe {
+    std::vector<ItemId> ingredients;
+    CraftResult result;
+};
+
+struct SmeltingRecipe {
+    ItemId input = ItemId::None;
+    CraftResult result;
+    float smeltSeconds = 10.0f;
+};
+
+// Registry of shaped, shapeless and smelting recipes. Constructing one loads the
+// default recipe set (planks, sticks, crafting table, furnace, chest, the five
+// tool types across all five tiers, torch, tnt and food/ore smelting).
+class CraftingRegistry {
+public:
+    CraftingRegistry();
+
+    void addShaped(const ShapedRecipe& recipe);
+    void addShapeless(const ShapelessRecipe& recipe);
+    void addSmelting(const SmeltingRecipe& recipe);
+
+    // Matches a 3x3 crafting grid against shaped recipes first (position and,
+    // unless disabled, horizontal mirror), then shapeless recipes (ingredient
+    // multiset, position independent). ItemId::None entries are empty cells.
+    CraftResult craftMatch(const CraftGrid& grid) const;
+
+    const SmeltingRecipe* smeltingFor(ItemId input) const;
+
+    const std::vector<ShapedRecipe>& shapedRecipes() const { return shaped; }
+    const std::vector<ShapelessRecipe>& shapelessRecipes() const { return shapeless; }
+    const std::vector<SmeltingRecipe>& smeltingRecipes() const { return smelting; }
+
+private:
+    void registerDefaults();
+
+    std::vector<ShapedRecipe> shaped;
+    std::vector<ShapelessRecipe> shapeless;
+    std::vector<SmeltingRecipe> smelting;
+};
+
+// Seconds a unit of fuel keeps a furnace burning; 0 when the item is not fuel.
+float fuelBurnSeconds(ItemId item);
+bool isFuel(ItemId item);
+
+enum class FurnaceSlotKind : uint8_t { Input, Fuel, Output };
+
+// State machine for a single furnace: input/fuel/output slots, a burning fuel
+// budget and smelt progress. Call tick() once per fixed step; it consumes fuel
+// on demand, advances the current smelt and moves finished output.
+class Furnace {
+public:
+    explicit Furnace(const CraftingRegistry& registry);
+
+    ItemSlot input;
+    ItemSlot fuel;
+    ItemSlot output;
+
+    void tick(float dt);
+
+    bool isLit() const { return fuelTimeRemaining > 0.0f; }
+    float fuelTimeRemaining = 0.0f;
+    float fuelTimeTotal = 0.0f;
+    float smeltProgress = 0.0f;   // seconds accumulated on the current item
+
+    float smeltFraction() const;
+
+private:
+    const CraftingRegistry* registry;
+};
+
+} // namespace vf